I'm no expert but I think everyone struggles w/ these at first. I'd suggest just keep doing them w/ nothing but the bar until you eventually find the groove and balance. You can stretch your shoulders, hips, ankles, etc., but I think you'll get it down if you just keep feeling it out.
A good stretch for the shoulders/chest is taking a broomstick overhead, holding the ends, and keep your arms straight while trying to rotate them back behind your head, like in the overhead squat position.