I am a pretty new DM, and I want to try my hand at a campaign from scratch. But I have no idea how to go about it? I don't know how to open the campaign in a way that's engaging and memorable, and I don't have a plot or even a location. I know I want it to be offbeat/lighthearted, but thats about where my ideas end. (I wouldn't even know how to organize the campaign if I had any inspiration) If anyone has any tips or ideas, I would be really grateful!

Tip 1) Don't try to be perfect.

Tip 2) Plagarize, plagarize, plagarize. 

Tip 3) Plan for the next couple of sessions, don't waste time fleshing out the rest of the world until the players can reasonably interact with it.

"From Scratch" is an ideal that's not worth pursuing until you already know what you want. Start with a one-shot, or a short adventure, and then if that feels right, roll that one into the next. You will learn what your players care about and can use that to inspire your worldbuilding.

If you need rough inspiration, flip through the monster database until you find something level appropriate that excites you. Ask yourself what a party would have to do to encounter a monster like that. Build backward to get your rough "timeline", and then work forward again to add intrigue along the way. The party might deviate from that, but you will have something tangible to build upon.

First up, if you have no ideas then I'm afraid that I really advise asking yourself whether you have the creativity to make an entire campaign. To put it into perspective, I have written around 100,000 words of module for my players, taking them from level 1 to level 12. This takes hours upon hours of time investment to prepare, and you need to create all of it in your head. If at the very first hurdle you cannot think of anything that you want the players to do, then I don't know if doing this is for you. To run a successful homebrew campaign is a huge step away from running a module book: you need to create on a weekly/monthly basis. There is nothing wrong with running a module instead.

To put it in context, this is a bit like going to a creative writing forum and saying "I want to write a novel, but I don't have any ideas." Nobody can give you those ideas. The answer would be "You want to have written a novel, you don't want to write a novel."

HOWEVER! All that 'tough love' said and out the way, I'm going to read the subtext in your post as "I want to run a campaign but I'm paralysed by fears that it won't be very good and it all feels like it's too big to even begin." And if that's the case, then there are ways to work with that and get you started.

How to go about making a fun early adventure that can lead you on into a full campaign:

1) Decide on your favourite villain. Always start with the villain. What level do you see the campaign going to? Choose a final boss monster appropriate to the level you expect them to be, e.g. if they are to be level 10 when they finish, a CR18 boss monster will be appropriate. Just pick your favourite. Example: You choose a red dragon, nice and simple.

2) The end villain is not near the PCs. But it has a plan. What is its problem in life and what does it want? Work out what it wants. Example: The red dragon wants to reclaim its ancient homeland from the wizards who drove it out. 

3) What is stopping it having it, and why can't it just fly in and breathe fire on its enemies? Spread away from the villain's lair in terms of geography. Example: Our dragon was contained by five runic pillars that prevent it ever coming into the region.

4) What small-scale, local issue could involve the dragon's problem? Example: Some tribal goblins are using the pillar as an idol to worship. The dragon has sent a minion of its own to clear them away, causing fighting in the area, which threatens local farms. An ideal adventure for level 1 characters!

5) What small scale adventure can the PCs go on to resolve the problem, but which will also lead them into greater conflict with the villain? Example: The PCs are hired to drive away the goblins, but become embroiled with the dragon's underling who tries to have them destroy the idol once the goblins are cleared off.

6) Design enough content to get characters from level 1 to 3 and then you're good to go. Expand the world, the map, the content as you go: don't try to plan it all at once.

If that sounds like fun to you and you think you'd enjoy creating it on a weekly basis, then run a campaign and have a great time. But if that sounds like you don't think you'd have the ideas then there's nothing wrong with running a sourcebook/module game.

Whatever you decide, ensure you have fun all the time! 

1) Come up with an interesting scenario that throws the player characters together. For example, they're on a ship which begins sinking, or they're imprisoned together, or they're 

You don't have to start with a fully formed idea either. You can just start with something you think is cool. Flip through the monster manual and find something that interests you. Cool. One of those is now terrorizing the town. Come up with a few minor encounters; does it have minions? What does it want? Where is its lair? How do they get there? Is there time pressure? Maybe it captured one of the villagers and this is a rescue mission! 

Then, while players are doing the first adventure (which should take at least a few weeks), start working on the next adventure in your off time. Again, start with a creature or bad guy who interests you, ask yourself questions about them; who are they, what do they want, how are they going to get it? Etc. 

If at any point you want to start interconnecting adventures then you can start threading a larger story, but you are under absolutely no obligation to. 

I 100% wholeheartedly second Memnosyne's advice on plagsrism: definitely do it, it's really cool. Take inspiration from anything and everything you like. Pick apart pieces of them, recombined them any way you like. I once heard something say "A DM is only as good as the stuff they steal from" and it is 100% true.

If you've tried all that and it didn't work for you, or even if you don't feel like trying it because you're not comfortable with it, then no worries! No pressure. 

There's also no shame in running published adventures. Sure, they cost money, but not all of them do. There's plenty of "pay what you want" online-- DM's Guild is a great resource for these-- and I'm sure some googling would turn up old adventure modules from past editions that could be adapted to 5e if you didn't mind a little homework. 

My fiance always says you should try something three times before determining if it's for you or not. The first one is to shake off any nerves or anxieties you might have about being a first-timer, the second gets you more experience, and by the third you should have a pretty good idea of your feelings on the activity. I would say give it a try. 

When you're just starting, don't try to be "the best DM ever". Focus on learning how to be a good DM by watching how your players respond to what you do, listening to advice, and using resources well.

I would personally recommend using an existing setting for your first campaign- you don't need to know everything about it, because your players don't either. Just have fun exploring the world, fill in anything that you don't know with improvisation (take good notes so you don't trip up on it later), and let someone else do the heavy world building work.

The biggest skill you need is improvisation. Your players will do things that you don't expect (or maybe even don't want them to do) and it's a lot easier to adapt on the fly than prepare for every possible situation (and your players will find things you didn't think of, guaranteed). Be comfortable letting things get a bit out of control- let players do "fun" things, but also be confident in asserting when things need to follow game mechanics, get back on track, and move the story forward in a way that doesn't take away from player experiences.

Make sure that you and your players have the same goal: everyone having fun. Be candid with that; sometimes, players who are being disruptive, trying to "cheese" encounters, or otherwise being problem players will realize, when you explain that the reason why you want them to engage with your story is that you want them to have fun with what you've prepared, that they can go along with things. That frees them to play their characters instead of playing mechanics, and you don't have to fight your players on little junk that doesn't matter.

Remember to say no, but also remember to say yes: one player having fun by being overpowered can steal the spotlight from everyone else, and sometimes things don't make sense. Even a natural 20 isn't going to seduce the angry dragon (sorry bards), or make a wall open like a door, etc. That said, if something does make sense, even if it's not what you planned, it's good to say yes so that players have agency; they only have their characters and nothing else, and you have literally everyone else in the world. Be fair to them by letting them participate; otherwise they could just read a book.

I think those are my pointers for beginner DMs. Obviously, it helps to learn mechanics, but you can still have a lot of fun playing very fast and loose with the rules as long as you remember to work with your players and focus on what really matters for the game.

Have you run a published campaign?

You might want to try one of those first, to see how they work, generally. It might even be easier to add on to the end. If , for example, you run the party through lost mines of phandelver, and there’s some loose ends, or a party member has been invited to join one of the larger organizations in the realms, that can be the hook you use to keep the campaign going, after the official one ends. 

Thank you for all the great ideas! To clarify, it wasn't that I didn't have any ideas, I just couldn't find any that I thought were worthy of writing an adventure. But I will definitely be putting all of this advice to use, I really appreciate you guys helping me out :)

Try to keep the story open-ended. Players have a tendency to subvert around 70% of the story the DM plans. Keep your main plot points, and leave the rest open to new ideas.

On that same note, it's a good idea to design a world to have your characters play in. You don't need to make it detailed or even written down. As long as you have a map in mind, it's going to be hard for players to head somewhere you weren't prepared for.