We all want a good-looking physique. That being said, most of us train our arms and chest hard. But don't forget your shoulders. Broad shoulders fill out your clothes and make you look manly.

 
Here are some shoulder workouts for mass that I recommend for general fitness, not for athletes. (Training your shoulders frequently can take time away from exercises that actually improve athleticism.)

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Go heavy

Working in the 8- to 12-rep range is generally the best way to add muscle mass to most body parts (the one exception being legs, which respond better to slightly higher reps). But I firmly believe that muscles, especially the deltoids, also need to be subjected to very heavy weight to grow to their potential—a weight at which you can do only 5-6 reps. Go ahead and do lateral raises in the 8-12 range (even 15-20), but I suggest doing overhead presses in the 5- to 6-rep range at least every other workout. It's not that every set of presses has to be heavy; if you're doing, say, 4-5 sets of seated barbell presses, you can do your first set or two for eight reps, but then make your last 2-3 sets heavier.

Increase Metabolic Stress with a Superset of Compound Movement and Isolation

Another key factor for muscle growth is metabolic stress. Metabolic stress is caused by the buildup of a variety of metabolites such as lactate, hydrogen ions and creatine.

One way to tell if metabolic stress is happening is to create a "pump" in your muscle. The pump is basically caused by fluids building up in the cells and the accumulation of metabolic by-products. Also, more metabolic stress can be created during the lowering portion of a lift, which is why doing isolation exercises is useful.

How to do it: Pair a compound movement (e.g., Arnold Press) and perform it for 8-10 reps, followed by an isolation movement (e.g., Lateral Raises) for 8-10 reps, with emphasis on the lowering portion.
 
 Utilize rest-pauses on presses

As intensity techniques go, I think drop sets and supersets are great when doing front-, middle-, and rear-delt raises. On overhead presses, however, my favorite technique is the rest-pause. The reason behind this is with rest-pauses, you never have to lighten the load—you start with a heavy weight and stick with it for the whole set. To refresh, here's how to perform rest-pauses: Pick a weight for a Smith machine overhead press with which you can do about six reps. Do a set of 4-5 reps, rest 15-20 seconds, and then do 2-3 more reps with that same weight. Rest another 15-20 seconds, then do another 2-3 reps. At that point, you'll have done 8-11 reps with a weight with which you could normally do only six. These tips will help spark growth in your shoulders, so give them a try next time delts day rolls around. Follow your pressing moves with high-intensity laterals and you'll have the best of both worlds: size and definition.

Perform a Shoulder Isolation Exercise 4-5 Times a Week to Increase Frequency

An increase in exercise frequency can further promote muscular hypertrophy. But don't get carried away. Performing Overhead Presses every other day might cause you to have banged-up shoulders.

Opt instead for an isolation movement and perform 3 sets of 10-12 reps 3-5 times a week to increase frequency and total volume. The Lateral Raise fits the bill perfectly because it's joint-friendly. Start with 3 times a week and slowly increase to 5 as you progress.
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How to do it: Perform 3 sets of 10-12 reps of Lateral Raises 3-5 times a week.

Excercise                                                         Sets             Reps
Smith Machine Overhead Press                      4              5-6*
Arnold Press                                                      4          10,8,6,6
Barbell Upright Row                                        3                 8-10
Dumbbell Lateral Raise                                   3             10-12
- superset with -          
Dumbbell Bent-Over Lateral Raise                3             10-12

* On your last two sets, perform 2-3 rest-pauses.