First off, hello and welcome to BB. I would advise you to read the Game Manual
http://www.buzzerbeater.com/community/rules.aspx?nav=Rule..., and to do so in small bits. There's no need to try to read it all at once.
Second,
INVEST IN YOUR ARENA. I made the mistake of not doing so when I first started, and my profits suffered as a result. You've found the forums quite early, which is a good sign.
A third thing I will advise you to do is not to buy high salaried players, especially the ones you see for cheap prices. These salary monsters will cripple your team. Also, don't buy players just because they have high potential. An 18 year old player with star potential can be trained faster than a 25 year old with hall of fame potential.
As the draft is about to take place, don't be so quick to pull the trigger and buy. If you are patient and looking, you will probably find a couple of good prospect that won't make you break the bank.
Good luck, and remember that BB is a marathon, not a sprint. Happy playing!