I had the best luck when not moving the crab at all. Next was to move it only a smidge ... like a 1/2 inch ... more a shudder than a strip.
You are welcome to use the patterns I tied for Eleuthera ..... Turnaffee (sp) crabs, flexo crabs and small epoxy guys. They are just collecting dust up on my bookshelf.
A word of caution .... they didn't work very well for Bull Sharks.