Well you first need solid routines for chest and back because the front and rear delts should get a lot of work from that. So if you are doing bench and rows (we're talking barbell and dumbbell here, not those girly machines), you should be good there. Then 1 set of overhead press and 1 set of rear delt rows should be all you need for front and rear if you are doing high intensity. If you're not going to failure then maybe 2 each. For upper traps a couple sets of shrugs will do. Then lateral raises are good for lateral delts. I do as few as 2 sets when going to failure and as many as 6 when doing a modified German Volume Training.
The biggest problem I see with shoulders is people don't do lateral raises right. You need to do them like this.
http://exrx.net/WeightExercises/Deltoid ... Raise.html
Upper traps get worked a bit with this, so no need to do crazy volume on the shrugs. Laterals get a little work on overhead too, so don't get to crazy with the lateral volume either. Keep in mind too many sets will kill your progress and ruin your joints and tendons. Less is more with natural bodybuilding.