First and foremost, you are a newly formed team. The starting crop of players that you get are usually crappy, and since you are starting out in D4, I suggest that you focus on getting 2-3 18 year olds with star to allstar potential. You also really want to build your arena, as this is your biggest moneymaker. READ THE GAME MANUAL. IT WILL HELP YOU UNDERSTAND MANY THINGS.
Make sure your guards have HA/PA that is at least at strong, and that your bigs have inept or higher HA/PA. This should cut down on turnovers.