I'd suggest getting back into doing full-body workouts 2 times a week for 2-3 weeks, then up it to 3 times a week.
Go LIGHT on the weights (maybe even using no added weights for some leg work, like squats and lunges)...you may have to put your ego aside for this (I find that I have to right now, as I'm just getting back into regular weight work, after taking pretty much the whole summer off of any formal weight work). Start by using weights that would allow you to do 2-3 more reps than you finish with. Don't go to failure. And focus on perfect form (help your body develop muscle memory for the perfect form while using the light weights, then it will be more automatic as you progress to heavier weights).
When doing upper body work especially, be sure to keep your shoulder blades back and down (scapular retraction), which can keep you from shrugging your shoulders (which can cause trap tension), and will also keep your shoulder in better/safer allignment.
Put longer breaks between sets as you feel you need (as Cathe says "a rest, not a vacation"), and make sure your muscles are ready for the next set before continuing (some of Cathe's workouts have a rather rushed feeling between sets, IMO, like the Pyramids, and I will let Cathe and crew continue into the next set while I recover a bit more, then back-chapter to catch up). Do some dynamic movements during this time (especially for the upper back and shoulders) to help keep the areas loose (but no long static stretches, which could impede your performance).
Some exercises to choose from that you might find helpful (if any don't feel good, don't do them!):
1) shoulder rolls : up, back, down, forward (I usually do them in this 'backward' direction, because it also seems to help open the front of the body more. If I do any in the 'foward' direction--up, forward, back, down--I always do fewer than I do backward, and finish with some backward ones. I don't want to do anything to encourage forward rolling of the shoudlers or a 'closed' front of the body). Repeat for a count of 8-10.
2) front-and-back claps (not their official name, I'm sure!): clap your hands in front of you at shoulder height, then behind you, as high as you can (progressing to as close to shoulder height as possible). Keep the movement loose, and don't shrug your shoulders while doing it.
3) shoulder swings : swing your arms up in front of you, so at the end of the move, you look like you're about to bow down to someone and say "I'm not worthy!". Hold in the upper position for a beat or two, then let arms swing down for 2-3 swings, then repeat.
4) "pot stirrers": bend over and let one arm hang. Make circles with the hanging arm, first in one direction, then the other (clockwise/counterclockwise). Keep the movement loose.
5) chest and shoulder opener: reach your arms above you, as in 3, then bring your arms down, leading with elbows (the arms will be in a goalpost formation) and opening the chest and front shoulder area as you stretch the elbows back and down.
6) shrugs: shrug your shoulders, then press them down to release the tension. You are creating tension here, only as a prelude to the release.
(Some of these ideas --3, 4, 5--come from Tony Horton workouts: I find he has some very effective moves for loosening the shoulder area. 2 is from a kettlebell workout by Steve Cotter).
HTH!
