So I took the offer to dm a game this February, and I now realize all of what I’ve gotten myself into.  I have a slight idea of the plot.  BBEG is a green dracolich whose bidding is mostly done by a lvl 20 Dragonborn Warlock of the undying and his minions.  Any advice for me that involves the plot or general DMing?

I've only hit session two going to session three but the biggest thing that I'm glad I did was make NPCs with depth that made sense for the environment they were in. Knowing your NPCs characteristics allows you to react as them in a believable manner when your players do something unexpectedly this also allows you to push narrative or even make new rails for the party to go on. 

Some of the other threads on here are great resources, but I'd point you to two Matt Colville videos in particular for villains in campaigns, since that seems to be your main concern.

Runing Epic Bad Guys: https://www.youtube.com/watch?v=-BZAjzUBYmU

Bad Guys!: https://www.youtube.com/watch?v=FUrlRZu2uCc

The rest of the 'Running the Game' series is great, too.

For my advice, I'd say early on, the BBEG dracolich is still in the early stages of things. What's going on early on is likely at a very low level, plans executed by kobolds or other minions of the minions of the minions of the BBEG. I like to seed clues and hints, and even have NPCs do or say things, or possess important-seeming items without having planned for what they mean, and write them down so that later I can reach back and make it look like I had everything planned out from the beginning.

I'd also advise to not have everything planned out from the beginning. Inevitably events of the game will throw any plan you have into the trash. What makes you look like a machiavellian genius GM is to give yourself lots of hooks throughout the game but only reach back to use them later on, when you can retroactively make a connection. That way, the players, seeing things linearly, will think you've had this master plan all along.

Minor example:  A low-level necromancer is raising specific individuals from graveyards, all of whom have the same occupation, say, blacksmith. On the surface, the necromancer thinks that blacksmiths make for the strongest undead minions because they're typically very strong. This sort of thing tends to satisfy the players, but much later on, the PCs learn that the necromancer archmagus who had been the lower level necromancer's master, has been seeking the corpse of a legendary smith who once forged the only blade that can slay a god. The original blade was destroyed by the gods long ago, but the archmagus necromancer wants to raise this smith's corpse as a servant so that it can forge him another such blade to use in his attempt to usurp one of the gods. 

It's not a great plot idea, (it's got a lot of holes in it and doesn't bear up under scrutiny)  but it serves as an example of what I'm saying. You don't know about the archmage necromancer or the blade, or his plot to usurp a god by murder during the first encounter with the blacksmith-corpse raising low level necromancer, but there is an odd detail with more than one layer to it that you can exploit later and look like you were planning these things out all along.

Thank you. This should help me a lot.  

I still need to know from any of you previous DM’s if there is a template that you use to plan or run by campaigns. Any ideas that could make this more simple for me? Please?

If you’re just DMing a single game, this is a lot easier than trying to keep a whole campaign on the rails once the players get hold of it.  Just think in terms of encounters. There’s an Encounter of the Week page here on DnDB that keeps a pretty consistent template: Present a few solid NPCs, present a bad guy, present a reason you need to stop him, and make sure the party has the means to do so.

If you’re new enough to the game that DMing has you very nervous, I’ll submit that you’re making it much harder on yourself by running dracoliches and lvl 20 NPCs with minions.  I suggest running a lower level campaign for a first run if possible.  This may not be possible if everyone is wanting to continue using their existing lvl 15 characters or whatever, but still my advice would be use the simplest monsters that you don’t have to remember too much to run right.  You’ll be amazed how easy it is to start juggling initiative tracking, and resolving skill checks then realize, “Oh yeah, this monster should have been taking half damage from the rogue’s nonmagical attacks.” “Oh yeah, I forgot that you all should have had to make CON saves every time you start your turn in melee with this.”

That’s all fine.  It’s part of the learning process, and nothing to get down on yourself about. I’m pretty sure every DM has looked backward by the light of experience to see they’ve missed stuff that today would be more obvious.  But there can be less of that stuff if you start simple.

So, the best plot help I can offer you is “What is going on now, regardless of PC intervention? What would happen if they didn’t get involved?” If you can answer those things, you can begin. Let’s say “The Warlock is sowing mistrust amongst the kings of the continent, urging them to go to war with each other. His master, the Dracolich, is convinced that humanoids will kill themselves off, leaving their wealth and land unattended. If no one discovers the plot, the nations will go to war. If they are destructive enough, the warlock and his minions would sweep through the city, killing off all that remain and amassing their wealth.”

Now we know we can plan scenes that put the players in contact with their plans. At a tavern, a jilted ambassador for the king rails about some new hot-shot vizier who has the king’s ear, getting him all scared of the neighboring kingdom’s intentions, when he knows from being there in person they are peaceful.

Enemies are encountered trying to enact some form of sabotage or terror, bearing evidence that incriminates Neighborland (though, investigation would reveal these are not Neighbors, but do have indications of being cultists—of some strange group).

They go visit the king. Warlock is there. King very agitated. “If you want to be of service, I need more spies on Neighborland.” Now they have a new choice. Go spy (where they will learn Neighborland has been getting the same intel about “Kingdom A” from a new vizier that sounds just like what we heard before.  They are nearing declaring war.) Or they confront the warlock there in front of the king. Likely, the warlock escapes and goes to Neighborland and moves up the attack timeline from their end. Or they confront the warlock, and when they lose, the king has them put in prison, and we go from there.  OR they somehow kill him, but not before he warns them “My death matters little. My master is inevitable.“ And you carry on the dracolich’s plan with a new NPC.

All the while, the same plot remains.  They’re just experiencing it based on their choices.

I would suggest that you do not make an endgame BBEG with a whole planned campaign trajectory on day 1. Even experienced GMs often do not do that, and an inexperienced one probably should not. I say this as someone who almost always gets over-ambitious with such things, so I can speak from (painful) experience.

I recommend starting off small... create a starter town and the immediate surroundings and populate it with some level-appropriate points of interest (POIs). Then let the players start by just exploring those POIs and as you go, you can build up the world beyond this. Maybe a BBEG will suggest himself or herself as time progresses, or maybe there really won't be a single one. That's OK... back in the day we just used modules that had their own stories and glued them together (figuratively) to make a longer campaign. That's way easier in terms of overhead than trying to plan out some big thing with the BBEG and such.

Thank you. I will try to make sure not to overwhelm myself. There is a reason everything is high level, though. I simply want my to 1. Let the PCs get creative with character design, 2. Allow myself some room with encounters, and 3. Make sure no one gets bored (Including myself)

Your motivation you wrote for the dracolich is wayyyyy better than what I had planned, so I’ll probably use it with some tweaks.  (The BBEG fight I’m thinking probably won’t be until all the PCs hit max level, so I’m putting off his interactions in the back of my train of thought) Thanks again

This is the best advice I can give a new DM.

 Yup. Colville's series on running the game. Watch it. Live it.

Any advice depends a lot on what you mean with campaign. Is it 5 sessions or 50? But here's some thoughts:

1. Don't plan everything a head. Start small. You don't need that much for the first session. However - put in some real effort after first session to work in any new ideas that occured.
2. Try to break down how they can beat the big bad guy into smaller goals. Not all of these goals need to be enemies that has to be defeated, and very important: the PC's doesn't have to achieve all of them. Before start, just have like 5 different ideas for the players to follow. Flesh them out later. (I use this method both for sessions and for campaigns. It "forces" me to also think about interesting paths the PC's can take to defeat the enemy, and not only create a cool adversary, but forgetting how to make it fun to beat him). Goals might include:
   1. Defeating an enemy/minion
   2. Acquiring an item (either to destroy it or to use it)
   3. Acquiring an ally/mentor and/or information
3. Think through what happens if the PC's don't achieve certain goals. Make sure this "hurts" the world in some way, but have a consequence that doesn't "destroy" your world.
4. Wait quite long before you give hints to the real bad guy! Be prepared that as soon as your players learn who this is, they will probably go after him!

Don't be afraid to make mistakes or try out things. Not everything will work as planned, but that's part of the fun with RPG.

And the most important advice: Be a fan of your players - if they come up with a cool idea to defeat your very well planned encounter - cheer them on and aplaude them! You create this fun together!

Best of luck :-)

I’ll make sure to start on the down low on the villain. I’m thinking they are hired to take out a mid-level kobold stronghold, but then they find evidence of a higher level of structure as well as the remain of a powerful political figure who recently went missing (noble). Then they would loot the whole place (knowing them) and find a book that keeps whispering legends and tales, which will (Hopefully) send the party on a goose chase for clues as more figures are assassinated or just vanish. 

I probably have planned to much already though, but that’s my rough sketch of what will take maybe 5-8 sessions

Quote from Drallop12 >>

I still need to know from any of you previous DM’s if there is a template that you use to plan or run by campaigns. Any ideas that could make this more simple for me? Please?

 Sure. Adventure modules. Plenty of them here on DND Beyond if you want large scale campaign books. Also check DM"s Guild for smaller adventures and one offs as well as larger campaigns.

I don’t plan the whole campaign all at once. I populate the world, give the NPCs objectives, motivations, and enemies, and then I start figuring out what they do based on that info. Then I start with one adventure. 

I always start by organizing the first adventure around whomever gives my their character’s backstory first. While that first adventure is going (the first 3-10 sessions) I start to drop in stuff for the other characters as well. By the time the first adventure is concluded the characters are usually around levels 3-5, and there are at least 2 other adventure plots already unfolding.

For example, if the first backstory I get is for the Cleric or Monk character the first adventure might be for the church/monastic order, but by the end of it the party has had run-ins with the Thieves’ Guilds, Arcane University, the army (for the Fighters/Barbarians/Paladins) and whomever else I need for the PCs to have excuses to opt-in. If the first backstory I get is from Rogue’s player, I start there instead.

Once things get rolling, because I know what the NPCs are doing and why, the rest of the campaign starts to write itself based on the PC’s decisions.