Quote from Demogorgon_Prince_Of_Demons >>

I'm interested in how to make good adventures that allow freedom for players, and aren't forcing them from one place to the next without their input.

I'm a relatively new DM, but in the Dungeon Master's Guide where they discuss adventure design, they mention the timeline method (I may be paraphrasing slightly). That is the method I used as a DM before I even had the DMG. Basically, you create a timeline of what would happen if the PCs do nothing. You can turn it into a flowchart that includes a few of the most predictable outcomes of PC actions at certain points, although in my experience, it's only worth doing the flowchart for what is likely to happen the next session; if you go beyond that, you'll be getting ahead of yourself and it won't be useful, because something unpredictable will happen. As these go along, you'll have to adjust your timeline to account for what the PCs have done. 

For a simple example, let's imagine that there's a serial killer that the party has to stop. You decide that on day one, he kills Person A, day two he kills Person B, and so on. Maybe on day three, someone is arrested for the murders, but then there's another murder, so that person is let go. You continue the series of events, and so on. Then let's imagine that the party gets involved, and they predict who will be murdered on day five, so they go there to protect the target. Now, the serial killer finds out that they're protecting the target, so he doesn't show and day six's target is killed instead. It's a cheap example, but hopefully it explains how that works.

Then, you can further improve this by:
1. Making the stakes so high that all the PCs would want to be involved. For example, in the first campaign I played, a cult was threatening the world by trying to summon a Cthulu-type monster. We didn't know that at the very start, but the clues were there that it was very serious (a terrorist attack, and zombies that the cult seemed to be the source of). 
2. Customizing the hooks for each of the PCs. For example, in my campaign's first adventure, there was a plague, and the party had to find the cure. Two of them joined in because they were immigrants looking for work and had the right skills; one joined because her mentor had caught the plague and asked her to see if there was something she could do; another joined because he was imprisoned, and was offered freedom in exchange for helping the cause; and another was sent by a nobleman he was friends with.
3. You can also incorporate motivations for each of the PCs. Some are motivated by money and treasure. Some are motivated by excitement. Some are motivated by trying to do what they think is good. Some are motivated by something else. If you provide motivations for each PC, then they will go along with the adventure. 

You need to be prepared to adjust your plans session to session, because a party is unpredictable. And another thing you can do is provide a couple of different adventures that they could choose from (for example, stop a bandit gang or look for a kidnapped person) so they can take their pick between the missions, or do one and then the other.

Hopefully that helps! I love talking about this, so I'd be happy to elaborate. 

How much agency should a DM have in a player's backstory? For example, if a character has a loving noble father, with no hint of any illegal going-ons, should the DM be allowed to say his father was actually a crime lord? Or a dead father become a secret agent for the upper planes by going into the nine hells? How much control should the DM have on player's arcs/backstories without stepping on their toes?

As a relatively new DM, I would love some advice on helping new players develop backstories and incorporating player backstories into the larger narrative.

Quote from YasasNeko >>

Would Prestige classes be making a comeback in future books?
I really love 5E, but even starting at later levels doesn't alleviate the feeling of every fighter is the same as the next but with a different fighting technique, or how every wizard is basically the same except for a few different situational abilities.

 Not sure about it, but I'm making a homebrew rune scribe class. It's on story and lore, though may be a few pages back. 

How do you build a summoner mage? What are the benefits and drawbacks?

How do you play a less than optional character and survive?

What's the best way to upscale beginner modules for 6-8 players?

How do you personally approach making a home brew race if you have to? Like the process you take I guess 

Quote from PitViperRMS >>

Whenever I'm teaching new DM's I insist on 3 things. Have a list of NPC, village, and tavern names, do not  ask for meaningless checks or checks you want them to succeed on, keep notes, even if it's just to make the players nervous. I'd like to know your top 3-7 list of good DM traits, as well as good player traits.

 Great idea! As a new DM, I think an article like that would be very helpful!

Also, a “How to Play Monsters” article on low level creatures like goblins and orcs would be nice

Has there been a new players guide on gold? In our current campaign we have heaps of gold but nothing to buy. After you get standard equipment there’s not really a reason to buy anything else, and our dm doesn’t know how he should handle the buying of magic items. 

I was Thinking about "DMing" Tomb of annihilation. And I am Doing it with inexperienced players any tips

When I say inexperienced I mean one of them only wants to be a barbarian. and the other Never plays characters correctly any tips James

Creating, Using, and World building with gods.

I'd love to see one on how to make open world, non-linear, choice-heavy adventures. It's something that doesn't happen often but that I'd love a guide on!

How do you start a campaign in a way that’s exciting for your players? I avidly followed your world building article but found myself lost after that.  

I want some tips on how to run different types of campaigns ( like dark or epic)

Quote from BramblefootDruid >>

Quote from Dungeon_Master_Lokito >>

I am a first-time druid. The DM and I are friends and fairly new to the game. We are not sure if the spell shillelagh would override the +2 dmg that you get from Duelist, the fighter trait, or will it stack? Also, if I had a +1 quarterstaff will Shillelagh override the +1 or will it stack?

 If it's plus one, it stacks. I'm not sure about the other one. 

 It stacks, damage buffs from different sources stack together. and a plus 1 to a weapon will also work when you use a different modifier for attack and damage.

I'm not a new player, but there is one problem that has caused many troubles in my past: how to deal with big encounters. As a player, I've been thrown many times in front of hordes of NPCs, and as a DM I've been twice in a situation where I had 20+ characters taking part in a single battle. Is there an easy way by the rules to avoid very long turns while still maintaining balance to the game?

I've tried stacking the characters into a single mob entity, but that sort of reduced balance as players still wanted to attack specific enemies for strategic reasons, and sharing HP/saving throws wasn't really a good way of solving the problem...

In response to SnipeElf:

Put something interesting in each room. Be it a description of some odd furniture, a trap, some NPCs, things that really don't look like they should be there. When you design a puzzle, start by how you want players to figure out the solution. Retrieve pieces hidden in different rooms? Solve a riddle? Decypher a cypher? Perform a specific task like a dance or a song? It's easier if you start from the goal, and then try to come up with clues about how the puzzle should be approached.

I like using symbols and mazes, even though story-wise it makes more sense for the hints to be kept by NPCs that would probably need those as a reminder to avoid getting hit by the trap or getting stuck outside. I don't think anyone would come up with a very smart door that can hide itself from view by magic and then just write around it the way to open it. What would be its purpose then? Make the players think about it logically, so that they may find clues for the puzzle in a credible context.

I'd like to see an article that deals with the question of "How do you handle NPCs as part of the adventuring party?" From NPC adventurers to trained hunting dogs. Hired porters to help carry the loot out back from the dragon's hoard, or apprentices learning the ropes from the party. Perhaps with a focus on when the DM should be controlling NPCs, and when the players should, or when they just shouldn't be used at all.

As an example, the Beastmaster Ranger has their animal companion that should be under the player's control at all times (unless maybe the character is unconscious, but maybe even then). But say the fighter uses animal handling to train a dog to aid in the adventure, when and how many handle animal checks ought to be required?

It seems like a category that doesn't get talked about in too much depth in the DMG, so it might make for an interesting New Player's Guide.