Stretching your calves (Gastrocs and Soleus) helps with ankle (achilles) tightness, calf tightness and pain under your feet.
Stretching is simple but needs to be done correctly.
Gastrocs muscle-straight leg stretch
Make sure your feet are parallel and not off at an angle.
Stretch for 30s to a minute
You should feel the stretch at the back of your leg just below your knee
If you have steps, hang both heels off the edge of the step or just one at a time.
Soleus muscle-bent leg stretch
Feet parallel again but bring your back leg forward so that you can bend it.
Stretch for 30s to a minute
You should feel the stretch at the back of your leg just above your ankle
If you have steps, hang one heel off the step and bend that leg. Just bend the knee not your back when you are doing this one.
Remember:
Stretching is not much use if you are only going to do it once a day!!! Do it a lot- 4 or 5 times a day is not unreasonable.
Check this for specific information on Plantar fasciitis.
There is also a self help download for heel pain and calf tightness.