Another way to hit specific spots is to use the Trigger Point Massage Ball. This works well, but it looses its shape quickly and can then feel a bit lumpy. You will find that using a tennis ball is not firm enough, but the massage ball is gentle and hits the points well. If you can tolertate a harder ball, then do what I do and use a golf ball on the muscles of my feet and other balls like a Lacrosse Ball for the glutes and other leg muscles. I have a variety of balls that I pull at when the mood fits from a softball to a little PINKY foam ball. There are a variety of prodcts, kits, and DVDs such as those from Trigger Point Performance that can make self-massage a breeze. Not mentioned inthe article are excellent products like The Stick or even for more concentrated work the Range Roller .
Here's a quick video showing how to use the Trigger Point Therapy tools (or other substitute tools) before going for a run or workout.
Here is a good presentation on the Rumble Roller.