The best piece of advice I can give here after the other comments above (all useful) is:
Pick for defensive skill.
Your C should be the player with the best inside defence. Your PG should be the player with the best outside defence. The PG also needs to have good passing. Then fill in the other positions (PF needs lots of inside defence and a little bit of outside defence, SF needs both as balanced as possible, SG needs outside defence).
I advocate this approach because anything you can do to reduce the number of points you need to score to win is a very good thing. It is a question of balance: you will still need to score points, but don't hesitate to put a player with only defensive skills into the line-up as a starter if his defending is really needed, or as a back-up. Adjust your line-up according to your opponents offensive preferences and defensive weaknesses.