When shruging, the attempt (or picture in the mind) is to try raising the traps as high as the ears. In other words, raise the traps as high as possible for you. At the highest point that the traps reach, hold that contraction for 2 seconds and than release the bar down to the starting position. You also want quick, powerful reps. Doing reps, for the traps, as quickly as you can influence that short range, but powerful , muscle group greatly. Also make sure the elbows are locked throughout the pulling motion of the traps, you do not want the biceps to help with this exercise in any way. Mistake most guy's make. Go forth the 12 to 15 reps range for BB'ing.
As stated before, the trap/shrug bar will match the purpose of most lifters. The thumbs are facing forward, in a more natiral and functional position.
Just my view, but the best execise for the traps are cleans. So many men really do not get the most out of regular shrugs. For BB'er, you might try a set of strict shrugs (elbows locked) followed right away with cleans. This form of SS'ing (actually pre-exhaust) almost forces traps to grow. 10-12 reps for this combo. Good luck.