Advice for D&D DMs: Be on the Players' Side 

Mike offers his thoughts and advice for D&D DMs on how to work with players instead of against them to run awesome D&D games.
Core principles
- Working with the players, not against them.
- You're not a competitor.
- The DM is an antenna to another world. We're the vehicle for storytelling.
- We're not the baddies. We're not our villains. We're not on the opposite side of the chess board.
- We're fans of the characters (Thanks Dungeon World!)
- The players understand about half of what's going on.
- The characters understand far more than the players do.
- The characters are smart and skilled in their roles. They have knowledge the characters do not.
- Fun doesn't mean just upward beats, it means risk and reward, upward and downward beats. Hard situations and hard meaningful decisions.
The DM's Job
- Build the situation around the story, not around the characters.
- Clarify that situation to the players. We're their eyes and ears.
- Help them meet their intent.
- Let the dice complicate things. They are the cold-hearted arbiter of the results of the situation.
- Balance acting true to the situation with the fun of the game; leaning towards fun and away from things that are not fun.
- The world and the story puts the characters in hard situations. The DM helps the characters make informed choices to navigate those situations.
Examples
- Warn them when they're walking into a potentially deadly situation.
- Assume characters that aren't involved in investigating a trap aren't putting themselves at risk.
- Let characters move that extra five feet if they can't quite get up to a monster.
- Ask the characters to make a group stealth check even if they don't ask for it if it makes sense that they'd be sneaking.
- Use characters passive scores to locate secret doors.
- Ask "are you sure" when they're doing something that clearly won't work or is clearly dangerous.
- Let players roll back spells cast if their character would know that it clearly wouldn't have worked. "A 1st level sleep spell won't be powerful enough to put them to sleep."
- Ask for the players intent and help them reach it.
- Offer deals: "You can make a DC 16 Intelligence (Arcana) check to channel energy from the unstable arcane node. On a success, enemies will have disadvantage on their saving throws against your spell. Fail and you'll take 2d10 force damage."
- Remind the players about advantageous terrain.
- Give players hints and clues about puzzles their characters would clearly understand.
- Remind players of things their characters would likely remember.
- Use skill checks and the characters' backgrounds go offer clues and tips.
- In complicated situations, offer strategic recommendations the players may not recognize.
- Remind players of impending dangers: "You have two rounds left before the orcish hoard falls upon you".
- Remind the players about items their characters possess that they may have forgotten.
- Offer suggestions for spell uses players might not remember or consider.
- Give characters inspiration or advantage when they take risky moves that move the story forward.
- Offer alternatives: "You can charge the first one and attack or you can ready your attack for the first one to charge up to you and stay close to your protecting paladin."
- Clarify impossibilities: "Hard as you might try, this door is beyond your capability to break down.
Work With Your Players
- D&D is a cooperative game and we're part of that cooperative.
- We have to know when to let bad things happen.
- Build trust with the players. Don't violate it. Be on their side. Avoid "gotcha"s.
- The world is cruel, you are not.