Bowmaster 12,
I had the same problem. As always, I got some great advice from the knowledgeable shooters on this site. The advise that worked for me was this: Hold your bow arm out like you are shooting your bow. Now, keeping your bow arm up, pull your hand toward your body. If your hand hits your face, you will smack your forearm every time. If your hand hits your chest, you are using the correct form. Essentially, you have to roll your elbow out, instead of keeping it locked and low like shooting a compound.
Give it a try, it worked for me.
Good luck and Good shooting,
Dennis