I can't even do one due to lack of shoulder flexibility. Use a "snatch grip" when you do them (as wide as you can go). If you cannot maintain perpendicular with your arms throughout the movement then you need to do some preliminary work. Same with back position, heel lifting or pronation, lack of balance. It is actually a pretty advanced move, and jumping right in without having someone watch you form to see if you need a "corrective phase" may be an invitation to hurting your shoulders. I think that is what Standapart was getting at.