Well I started to get away from just hosting but it's good info so I'll leave it.
Host:
Always a good idea to set warpout to host only.
Always check respawns before starting.
After people join and you go through mission load assign people to their ships
You have to lock before people can choose weapons but once locked you can't move players to different ships.
Don't end the game until all players are dead or the goals are complete. If you die wait on them.
If your game isn't full try not to use the replay option. Give it a few minutes in forming just in case other want to join.
/kick can be useful at times.
Someone who pauses the game but doesn't answer may be stuck in limbo.
Remember you have to assign ships and weapons to AI before you commit.
Playing a TvT or FFA rests difficulty to medium. Double check difficulty before playing coop.
All:
Lag bombing is considered a cheat.
Tab loading is also bad. Although a Pegasus with Helios can be quite useful at times.
Pausing except by the host is not usually a good idea unless for a really good reason.
If you don't know what to take in the mission ask, copy the loadout of someone who does, or use the default.
Don't leave the game just because your in observer mode.
Don't bug the host to start the game. Patients is a virtue and he may be drinking a beer. See /kick above.
If you get stuck in limbo (die but don't get respawn or observer mode) it's a good time to pause.
TvT Host:
Always try to assign someone with a good connection and preferably not a noob to be the other team leader.
Both team leaders must lock before weapon selection can begin.
Just because the primary objective message comes up it doesn't mean the game is over. It's only a bonus.
Normal play is until all on one side are dead.
Normal respawns are 10. This came from squadwar. But a lot of people like 15.
TvT General:
No AI, AE, SD, mean no AI controlled ships, no Area effect weapons like piranhas, EMP, and infernos, or Self Destructing.
Support is usually a no-no unless the all support ships show up as the team that calls the first one bug has been fixed.
FISH = piranhas, FIRE = infernos
BTW Kara that option be put in the multi.cfg like the low updates was? It would be nice for standalones.