Its no easy task.
My advice is to learn it functionally.
Pick a movement, lets say flexion of the arm, first learn all the muscles that are involved eg corocobrachialis, biceps brachii, anterior deltiod and so on. Then one by one learn origin insertion innervation blood supply.
Its importatn to only learn a small amount at one time (sitting) make sure you only do one functional group. Give your self a time limit. Get real active. Use your imagination and actually see the muscles. Try palpate someone, its a simple test, it really helps.
Any spare moments you get, try and revise.
I hope this is helpful.
After i have studied, I often put myself in a relaxed alert state and photoread a page for a while, until i feel what the anatomy 'feels'like, then i combine that with a confidence that 'i know it'. Your mind has it all, don't let false beliefs stop what you know!
Good luck