2.) If possible don't roll the same class.
This is my only major letdown with the game, a huge disapointment. If you have 2 of the same class (ie 2 Troopers or 2 Jedi Knights for example) you will have to do every phased class quest twice. If that doesn't put you off then great, however for me doing the class quests twice would get old fast. You can just solo the class quest and team up again afterwards, which if that works for you awesome, however it didn't work for me as we wanted to team all the way up.
I don't agree with this for the most part. The class quests are meant to be solo quests and offer some fun challenging fights that are trivialized with 2 players. My wife and I teamed all the way to 50 but just solo'd our class quest (obviously did at the same time). I would argue that picking same class is actually better because you have 100% of the same quests. I am a tank and she is heals so for us it is even better, we do all the 4 mans with just 2 of us, as well as many instances. This offers an extra challenge that we enjoy.
So i would just add that people should not at all steer away from the same class