rule number 1: you are running the show
rule number 2: if they think you are in error, like the troll is not black, refer them to rule number 1. it is YOUR world and you get to change things around as you picture your world to be.
Some really handy tips for any encounters:
1) when they start to argue in the middle of a dungeon hall way or corridor, and they aren't paying attention to you. allow those that are paying attention to you to roll initiative, the others will suffer 1 round of surprise attack from pests (something they can easily defeat, but enough to make them shut up and focus on the thing that they are meant to do, or in the least hurry up their discussion, cause the longer they argue the more chances more pesky stuff arrives> that happen to be attracted by the noise.
2) if the story seems to bog down, don't hesitate to tell someone to roll against a related skill. ie knowledge history, knowledge religion, etc. If it's a puzzle/trap, have them roll a spot or search. Then give them a hint.
3) if you like to time when an encounter take place, set it. like 3 orcs are fighting but their buddies are separated in rooms a, b, and c. the orcs in room a are putting on armor cause they were sleeping, they take 4 rounds to arrive to join the fight. room b people were about to sleep so they show up 2 rounds later. room c people are still sleeping and you will need to roll listen checks per round to see if they wake up. if they do, they join the fight 4 rounds later.
This gives a running fight and still be low level but increasingly challenges the players cause they keep coming.
4) monsters aren't always dumb, but at low levels go right ahead and push it to extremes. An orc picking his nose, another using his sword to clean his toe nails, another pulling nose hairs and adding it to the stew he was making. It's all flavor text, but gives the players something to visually imagine. ALSO gives you time to grab the right stats for the next encounter or so since you are just talking. hehehe hands can still do things like write, or thumb pages.
5) use little post it notes to mark specific pages. they become markers for future use. like my PHB and DMG has post its on certain classes, equipment, experience table, magic items, npc attitudes, starting equipment etc.
6) always have blank paper to write on, use pencils. you can go back after a game and put them all together into a neat pile or notebook but during the game you will be scribbling down a lot of stuff, like the orc that got away has a missing left pinky cause the fighter cut it off when he disarmed the orc. you can use it as a future villian that returns for revenge or some such.
just little things. hope they help.
