ORIGINAL: honcho12
Also you may want to try a string supressor. In a hunting situation from a tree stand you can't always get a good stance and have great form. I use onemade by shawnsarchery.com and am very pleased with it. I have a Guardian and I try to practice from different positions I might have in the stand and sometimes I would get the string slap too, but the string supressor cured it for me.
Although I don't advocate using a String Suppressor just to keep from getting slapped they will help
Make sure everything else is right and then add a String Suppressor and enjoy all the benefits.
Dan