I prefer to use my hands, where possible.
Gives a much better feel and manipulation than any device - if you can learn it...
some very basic starting stuff...
http://velodynamics2.webs.com/selfmassage.pdf

I'll hilight, what is also highlighted in the brief article:
"always from distal to proximal, i.e., toward the heart,"
especially for long strokes
across the muscle doesn't require this directional concern...

look for more resources

self-massage really works