NASM as usual is absolutely correct, I personally will spend evenings foam rolling and static stretching both my soleus and calf muscles in the method mentioned above.
In addition to self myofascial release I also incorporate trigger point release as it is a bit more centralized and can get deeper than foam rolling. I use both techniques.
Trigger point release is extremely similar to a trigger point or deep tissue massage. Trigger point release allows you to get into areas that a foam roller will not. (not really calves but more things like upper traps, shoulder blades, ect. but I still use it on my calves)
For instance I will roll my calves and soleus and I can release the muscles well but if I pin-point a few areas that are ultra tender I can get even deeper. I will do foam rolling for an overall release and then use the Body Back Buddy to get in even deeper on a few areas.
Check out the link to the Body Back Buddy: