Tips for DMs

Being a DM usually means you have more responsibility than the rest of the players. Most likely, you'll be organizing and hosting play sessions and doing all the preparation. Some people are actually really into this, but it can take a lot of you time; don't let it take too much.

Have Fun

• If you get something wrong, your players won't know and won't care. They're having fun.

Minimalist Preparation

• Don't over-prepare. D&D can have varying degrees of structure, but it is still organic and spontaneous. Get comfortable with improvisation, then get proficient.
• Your players will miss characters and parts of the story or adventure accidentally and on purpose. Hense, don't over prepare.
• If you think about it, you can force anything on your players if you really want to, but be subtle about it.
• Keep your resources handy, such as the the adventure book, players handbook, and Monster Manual. Don't make dozens of notes you don't need.

Using the Modules

• Adventure and campaign modules can be dry and dense. Think of them as a manual for a tour guide. DMs are kind of like tour guides. Read it once for the gist of the plot, setting, and characters, then make notes on the parts you expect to reach before that play session.
• You don't have to follow the modules exactly. You can change, add, or not use anything you want.

 

Making Maps

• If you recreate maps, don't worry about getting it exact. What matters is if the map you make functionally represents the map provided by the module. Number of rooms, relative dimensions, locations of objects, doors, trap, etc., done. 
• As a practice to keep your prep time reasonable, you should freehand your maps at the game table.
• For realism, you can draw the rooms or areas as your players progress and discover them so they don't know what's ahead. Get tape and extra paper if you end up going off the grid.

Something About Creativity

• You're not telling the story, the whole group is. DMs provide a scenario and the group tells you what they do. 
• It's normal for one or more players to provide the scenarios and you tell them what the NPCs do. "I attack the king" is the scenario a player provided. What happens?
• Don't tell the players "no" if you can help it. If they want to do something really stupid, say "yes, and..."