How long should it be and what should I incorporate into it?

A lot of this depends on what level you are coaching at....

Stretching and footwork
Defensive Drills
Ball handling & Passing
Offensive drills for screening and shooting
Free throws
Inbounds plays
Press offense
A press if appropriate

Try to keep the drills short... 5-7 minutes, keep the kids moving and they wont get bored... when you work on team offense and team defense that takes longer.. maybe 15 minutes or more.

You need to have a good practice plan so you can cover the things you need. We always ended practice doing a fun thing so they wanted to come back.

I coached at the high school level and our typical practice was 2 hours long... it got shorter as the season progressed.

I hope this helps.