http://nicktumminello.com/2009/07/th...rcise-circuit/ on how to properly perform these. He saids Think about bringing your shoulder blades together (not up like a shrug). First use bodyweight to get the form down, then progress to a light weight. I also have tight upper trapz that are overactive (and levator scapulae), so I am working on the exact same thing you are.
Good trainers to learn from is Nick Tumminello, Mike Robertson, Eric Cressey, and Bill Hartman. I know there are other good ones out, but those guys are the ones I follow in newsletters and blogs and rely on and know about and trust. I am not allowed to give advice from my personal experience because I am not a PT or CSCS, but I can only say what those 4 guys have said regarding different things with links on where I got the information from.
Theres also another thread about this topic, but its in the training forum.
Upper trapezius deactivation if you want to check that out. theres some good advice in there.