I cannot stress how important a good warm-up you need.
The Title says it all... I injured my shoulder a while ago by not having a proper warm-up.
Never again have I engaged in a workout without having a blood pumping warmup.
Always climb your weight to your working set.
For today's shoulder workout I warmed-up with 25lbs dumbbells doing Arnold-presses for 10 repetitions, 40 lbs Military-press for 5 repetitions, 55 lbs for 5 repetitions, 65 for 5 repetitions, then Finally...
Working set: 75lb dumbbell Military press for 5 repetitions for a total of 5 sets.
My 6'4 Frost Giant of a friend, showed me a KILLER circuit workout that will Target every muscle head of the shoulders, it goes like this..
While standing tall with 10lb dumbbells on each hand, start doing front delt raises for 10 repetitions simultaneously. After those 10 reps, without resting continue on doing 10 more repetitions of front rowing, like you're rowing oars on a shredded viking boat. Lastly, still without rest! Hold the dumbbells close to your chest, and shoot straight out to the side of you for 10 repetitions..
Now rest for 30 seconds, and repeat this workout for a total of 3 sets.
At this point my shoulders are filled up with blood, and about ready to explode..
Onto the next workout!
I toyed with 20lb dumbbells for
Incline bench dumbbell rows.
5 gruesome sets of 20 repetitions..
Really gets the rear delt crying in agony..
Finished off the routine by shrugging dumbbells for a total of 3 sets.
Set 1:65lb dumbbells for 20reps
Set 2:85lb dumbbells for 20reps
Set 3:100 dumbbells for 20reps