The Warmup

There is a warmup suggestion on the crossfit website here.  Look at the workout you are going to do what joints/body parts are involved.  Also consider some of your major weakness'.  If you are not flexible and unable to get below parallel in the squat work on it.  Starting with some dynamic stretching is usually considered best.  Hold the wall swing one leg front to back 10-15 reps/leg pass throughs with a broom stick, twists at the hip as well.  If you are doing heavy lifts warming up the the target areas is important as well as doing lighter weights at higher reps to warmup and confirm your technique.  If you are injured the warmup is a good time to rehab/prehab yourself. www.exrx.net is a useful resource for finding exercises to help solve problems.