Gameplay
I won't bore you with details of how to move around and use powers and such. More importantly, you need to know the basics of how the game works as far as teams, missions, and leveling goes. Not only will this make it easier and faster for you to get in there, but you won't have to ask as many Noob moments like these:
Example 1
I thought of a way to go through missions faster and of course thought I was the first person to ever do it. It involved "using stealth powers to sneak to the end of the mission". I decided to call this revolutionary idea "stealthing". How dumb must the other players have thought I was.
I don't know the actual term if there is one, but it's commonly referred to as "sneaking", "stealthing", "turboing", "ninjaing", "ghosting" etc.
Example 2
After gaining several levels, I complained about how long it took to go all the way back to contacts after each mission. Someone asked me why I didn't just call them. I snappily replied, "Uh… what? Do what?"
Turns out that you can call a contact after checking in with them two or three times physically. That way you don't actually have to run back to them. That would have been useful to know in advance.
Example 3
At level 13, I realized that I picked some bad combinations of powers for my first Dark/Regen Scrapper. I Rolled a new Scrapper so I could redo the powers correctly because I didn't know about Respecs. Oops.
Avoid mistakes like these by learning some of the game basics as well as tips for being more effective in the little play time you have.