I've literally just started playing Mass Effect (about an hour's worth) and I'm having terrible trouble with the overall controls and abilities of my character and teammates. The tutorials weren't very clear or weren't available at all.
I'm having most trouble figuring out what biotics are and how to use them, how to heal only myself vs. how to heal my whole party, how to revive a fallen comrade, and how to build certain types of characters (I'm a vanguard, but my teammates are soldiers).