This one can be tough, especially for youth basketball coaches who enjoy focusing on the X's and O's but didn't realize the job sometimes comes with difficult player management issues.
First, I'd recommend talking to them one-on-one to see if you can understand what's causing the negative behaviors. Sometimes just lending an ear opens the door for a better relationship with a troubled player.
Of course listening alone probably won't solve all your problems. Eventually you'll need to be firm and provide some discipline -- in which case you can leverage your team culture, peer influence and senior leadership to encourage better behavior.
What kind of things do you do?