*I posted this in another forum, but it's solid advice on shoulder training. If you need help building shoulder mass then you should read this.
Delts are fairly straight forward. Try to steer clear of military press. Over head dumbbell press is more effective at creating overall mass in the deltoids because it distributes the force evenly between the anterior and medial head, whereas military press is mostly driven by the anterior deltoid. This has everything to do with where the arms are positioned relative to the body. If you want instant proof of this, raise one arm in the position it would be in at the beginning portion of a rep for military press. Take your other arm and place it on the anterior deltoid and compare the amount of tension on the anterior and medial head. You'll notice that the front of your shoulder is tenser than the side. Now do the same thing, only this time move your arm back so its in line with your body the same way it would be during an over head dumbbell press. The force is now evenly distributed over both heads, thus causing more overall mass in the shoulder.
Overhead dumbbells: The Importance of your Spotter
Whenever I press dumbbells in excess of 70 lbs. I always get a spotter to help me with the setup. There's no sense in wasting all that precious energy doing it yourself. I suggest you do the same. You can also have your spotter there to help you force out a few extra reps. Pressing heavy free weights over your head is potentially very dangerous, so keep the forced reps down to two maximum. Remember they're also a valuable source of motivation, so pick the right spotter. It can mean the difference between a rep or two, and at such a high level of intensity, those reps are worth their weight in gold.
Obviously you want to keep things heavy if your looking for mass, so it goes without saying that your overhead dumbbell pressing should all be done with your ass in a seat. Have a mild angle to the bench, not a straight 90 degrees.
Warming Up: The Key to a Great Shoulder workout
In my opinion, you're only as good as your warm up. Because the shoulder is a sensitive area of the body, it's absolutely key that you warm up correctly. It's also rather difficult to stretch the deltoid, the medial head in particular. I recommend warming up with light dumbbells and not to rely on static stretching. There is research that shows static stretching can decrease strength when done before a set. Save the static stretching for at home, just not before or between sets. Begin by pressing only your arms above your head. Do this in a controlled manner for as many reps as it takes you to feel comfortable. For me that's usually just shy of 20. Then pick up the 15lb dumbbells and do the same thing. Climb through 15's, 20's, 25's, and 30's, progressively lowering the reps. At this point your shoulders should be ready for anything.
Here is a sample of my current shoulder workout:
Seated Overhead Dumbbell Press
Warm up (as described above)
Set 1
70's to failure - with spotter. At this weight, for me failure occurs around 8 reps (I'm not on steroids). You should choose a weight that causes failure in this range as well.
Set 2
70's to failure + 2 forced reps
Immediately pick up 2 15 lb dumbbells and perform seated lateral raises until failure + 2-4 forced reps, courtesy of your spotter. (Make sure to thank him/her for all their help.)
Seated Lateral Raises
Set 1
25's to failure
Set 2
25's to failure + 2-4 forced reps Immediately followed by 15's to failure + 2-4 forced reps
That's what I mean by shoulders are pretty straight forward. It's just two movements. Sure you can throw in all types of front raises, machines, military presses etc. But if you are looking for mass, this is all you need. The key is to keep the intensity as high as possible. It's also important to point out that the posterior deltoid should NOT be trained on shoulder day, but rather with the back. This is simply because the rear deltoid is not used whatsoever when the body needs to press weight over the head or raise it laterally. I train my rear delts at the end of my back workout, right after rows. If you're still training your posterior delts on shoulder day you need to switch it to back day. You'll notice the difference.
However, the single most important aspect of training your shoulders is your form (same for everything else you train as well). You should be performing each rep with a controlled 3 three seconds during the eccentric (negative) portion of the rep, and an explosive one second through the concentric (positive) portion of the repetition. No matter how difficult the movement becomes, never stray from this. That's what keeps the intensity at a truly high level. Regardless of how tempting it may be to swing the dumbbells by using momentum or falling through the negative (never do that) you should never deviate from solid form. Otherwise it's just misdirected and wasted energy.
I personally find the deltoids to be the most aesthetically pleasing part of the body, so I take extra care of my delts. I hope this information helps!
One last thing, when I move to seated lateral raises and I'm on my last set, I like to ask a fit attractive woman to help guide the set and help me force a few extra reps at the end. Women always seem to be more than willing to help on this one and it's a perfect movement for their help because there's reletively low weight involved. It's a solid way to begin a conversation with a good looking woman and kill two birds with one stone.