What exercises do you recommend, if one's main target is broad shoulders (and chest too, but less priority)? Does reducing exercises for other muscle group help? Any other tips?
Source: This blog.
I can't believe nobody has mentioned this yet. The muscle that gives the overall appearance of 'broad shoulders' is the 'Latissimus dorsi' or your 'lats'. Wide pull-ups are a great exercise for targeting this region as well as your shoulders (deltoids), arms (both biceps and triceps), and forearms (from gripping the bar).
For proper form be sure to cross your legs and lock your knees to prevent swinging or cheating by using momentum (no frog kicking for 'just one more' allowed). Raise and lower yourself in a slow/controlled manner. I can't stress how important it is to maximize both the raising and lowering during the exercise. Forget about the number of reps you can do (this isn't an exercise to impress the 'how much can you bench?' guys at the gym). If you do them 'right' you'll feel it.
Note: If you don't have the strength to pull yourself up to the bar yet, grip the bar and start by jumping up the position where your eyes are level with the bar, then lower yourself down slowly. This will help you build up the strength needed to be able to do the full motion.
If you're going for more of the 'thick neck' or 'no neck' look, or what I like to dub the 'meat head' look you'll want to target your 'Trapezius muscle' or 'traps'.
The exercises that exclusively target your traps are:
It may surprise you but the 'broad shoulder' look has little to do with your shoulders and more to do with upper/lower body proportions.
Update: Added some more specifics about the wide pull-up exercise including tips on proper form and and easier variation for those who don't have sufficient strength to do the full motion yet.
Another option for building your shoulders is the Shoulder Press.
Front Raises will also help build your shoulders.
To build any muscles, it's important to do a variety of different exercises that target different muscles in the same area.
As @Adam pointed out, military presses and exercises that target large muscle groups is critical to building mass. However, make sure you don't neglect the exercises that help target and strengthen supporting tissues.
Taken from here:
Standing Military Press
Join a dragon boat team! Seriously, if there is a dragon boat paddling team in your area, consider joining it. I paddled for several years, and every person who started paddling and came to practices regularly grew broad shoulders, even if they started scrawny. It's an amazing full-body workout, and results in much stronger shoulders, abs, lats, and other parts of the body.
YOU WANT TO BE AS STRONG AS THESE MEN
LOOK AT THEIR SHOULDERS
If you think this might be a good experience, feel free to ask me questions. If you live in the US, the US Dragon Boat Federation has a listing of many of the teams in the US, and you can always try just searching on Google for teams in your area.
One unexpected thing that worked very well for my trapeziums was carrying a heavy backpack during my University days.
I had a business-styled backpack with a flat back, with firm, comfortable and thin belts that would use the clavicle as hook and place all the weight from the backpack on the shoulder, which I believe wasn't designed for the heavy load I had to carry around. I generally carried around ~15kg/~33lbs: my 17'' laptop, it's AC adapter and a lot of heavy books. Every day, I would stand for several hours and spend an hour or two walking in a fast pace.
I would consider this as a supplement to your shoulder exercises. I had sore muscles the first month, but afterwards I wouldn't ever even notice the load I was carrying and it felt I could go for much much more before I'd feel any strain.