#1 - Thoracic Spine (Mid/Upper back area)
This is a big one, which I recommend to pretty much anybody that will listen. I personally hit this one twice a day, and if I didn't have a job I would do it 40 or 50 times a day. Of course, if I didn't have a job I probably wouldn't NEED to do it quite that much. Anyway, here's how it's done:
Lie back-down with the roller positioned horizontally beneath your shoulder blades. Simply roll back and forth with your hands crossed in front of your chest or extended overhead. A good goal is to try to get flexible enough to have the hips and the back of the hands touch the ground at the same time. Note the pain face: this is key to making sure the proper muscles are firing and for safety in all theses movements.
#2 - Quads
This is another area that tends to get very tight and sore with all of the squatting, running, and jumping that you do. You can't hit this area enough ... especially if you're experiencing any type of knee pain or tightness in the area.
Lie face down with the roller positioned anywhere between your knee and your hip. Roll up and down and side-to-side. Spend time in the areas that hurt the most ... if your face doesn't look like Roger's then you're doing it wrong.
# 3 - Hips and Booty
Once again, these are spots that take a lot of abuse with all of the violent hip extension, pulling from the floor, and squatting that we do in our programs. And remember, using a foam roller for this is way smarter than using the edge of a counter-top at work ... and you'll get less strange looks.
For this one, sit on the foam roller with the leg/hip you are working crossed over the other. Lean towards the side you are working on, again moving up and down and side to side. Stick on any areas that feel especially rough, and try not to cry.
#4 - Calves
Unfortunately for me, this movement does not add any size to your calf muscles. However, it's a great way to keep everything feeling good after a lot of double unders, box jumps, or olympic lifts.
Simply place the meat of your lower leg on the roller and get after it. Up and down hurts like hell. Side to side .... I can't even think of an adjective for the pain. Good luck.
Those are the big 4 to hit in my opinion. Obviously there are other ways to use the roller, but if you only have 5-10 minutes after your workout these are a good way to get some bang for your buck. As for when to do it, half of the world will tell you it's great before a workout and the other half will tell you to do it after. This is something you'll have to play with yourself. Just find time to do it, and enjoy!