I keep trying with "My Player", but i am so bad at it it's unreal. I can't get to grips with the shot stick (on Ps3), which means i always get a low team-mate rating as i don't score many points. I managed to get drafted by the Lakers in the 2nd round, and i'm currently playing the Summer Circuit, but i'm much better at Association mode so i play that more.
My Player is always rough to start up with. And if you don't improve quickly, your player may quickly be relegated to the D-League. On NBA 2K10 I re-started my player career about 2-3 times before finally getting a hang of the system.
If you can't get in terms with the shot stick, try the shot button (I think it's square on PS3). I personally still use the shot button for all shooting except for dunks, where I use the stick (since you can point it in different directions for different dunks). What player type are you?
Also, here are some easy ways to get cheap teammate grade boosts:
1. Set a lot of screens. Setting a screen on the ball is good but setting an off-the-ball screen has a lot of value. If you set about 10-15 screens a game, your grade will probably jump a whole letter (C+ to B+, etc.).
2. Pass around the perimeter. As long as you are passing around the perimeter, you can accumulate a few "good pass" points.
3. On defense, call for double teams by pressing and holding L1. If you have a successful double team then you get points. I usually do this in the low post, since I'm a PG and a bad post defender.
4. Take a shot when you are wide open. Even if you don't knock it down, you will get teammate points for "Good Shot Selection".
5. If you want cheap easy points, when you're on defense, start running back for the fast break as soon as the opponents shoot a mid to long range shot (pretty much any jumpshot). The CPU is very good about finding an outlet pass and these are pretty much uncontested baskets (layups) that will give you "Good shot selection", "Fastbreak" and "Dunk" if you end up dunking it. Once you get better, you should stop abusing it because you can end up scoring like 70 points a game.
Anyways, lemme know if these tips help you. What player type are you? I'm a PG and generally speaking for PGs/SGs you should be looking to improve your shooting skills first ("shoot in traffic", "shoot off dribble", "mid-range shot", etc.). These are typically cheap.... 3-point shooting is expensive and you should try and get these through the player drills.
Good luck!