For finding friends, use the /search command. Sort by level and just start sending people tells. To me the most fun part of the game is meeting people, teaming, and seeing how others play the game....Sometimes you manage to form a team that is shockingly powerful and synergetic...SOmetimes you get someone who has a bad build and can't play....It is the random nature of these things that brings me joy.
"Hey do you want to join a level X mission team?" Is all you need to send. Then just run your missions....Before each door spam something in /b like "3 Spots on mission team, PST if interested"....And remember you can use /search inside the mission door as well.
YMMV
Also, Welcome to the game! If you are ever on Freedumb , look me up I would be glad to team with you any time.
Nearly pointless to stick my head in here now as there's so much great advice (and this was sort of mentioned as well), but one thing I read ages ago about Doms (which are a great class btw): never lead off with an attack, you always lead off with a control power such as a hold, confuse, etc.
Good luck with the game 
Arc#314490: Zombie Ninja Pirates!
Defiant @Grouchybeast
Death is part of my attack chain.