if nothing is going on ill just do some mobility stuff for the joints ill be using that day to get the blood flowing. then ill do a bunch of light sets of the main compound lift im doing. in between the light warm up sets ill do some more mobilization. then i just get to my real warm up sets.
other times i might run. I might have just gotten done doing some judo or bjj. who knows..
Even the nice dense foam rollers wear out. I bought a 3' long piece of 6" PVC. It hurts a little to get used to but now I will never go back to foam. It cost me $15 too and will never wear out. I use it every day multiple times daily. Helps keep my thorasic(sp?) spine in line too.
under the armpit is the best for me because i have alot of tightness in there.
Do a youtube search for Defranco's shoulder stretching and also Diesel Crew Shoulder rehab. Lots of great stuff in those for upper body and rotator cuffs.
Currently I do some static and then some kenetic stretches, followed by some quick body weight exercises just to get blood flowing and joints warmed up. Been checking out a few new things....anybody ever try yoga for heavy lifts. Heard some colleges and pro teams implementing it.