I don't do much "dynamic stretching" prior to my workout. I just do bar work - overhead squats, snatches, front squats, drop snatches, etc. That's because my flexibility is generally pretty good and I can get into all of those positions pretty naturally. Some people like to do dynamic stretches pre-workout to get loose.
Static stretching I love to do on off days and I try to target my weak areas. Chest, hip flexors, and hamstrings I always static stretch just because tightness in those areas is so easy to develop with a sedentary lifestyle.
There's a great article in the stickied section about flexibility and stretching. Personally I think it is the most overlooked aspect of training and possibly the foremost reason that people get injured while training.