Delts are a great place to start because it's idiot-proof. Don't flex, obviously and know exactly where the stick is going. Quad is a dream; so easy and smooth, you have both hands available and fairly painless. Even a 22 or 20 isn't bad at all. Make sure the spot is IM and deep in the belly. Don't get those 3/4 inch pins because it, more than likely, won't get deep enough. Extend and join your fingers and place your palm on the very top of your thigh facing downward along the outside of the patella. The sweet spot is half an inch up and half an inch down (for most people). Grab the muscle, breathe in, stick, aspirate, SLOWLY sink it and wrap an alcohol swab around the needle, loosely grasping with the other hand's thumb and index as you pull it out to ensure it isn't shaking or moving up the outward pull. ED or EOD sucks as you're moving around constantly, but you'll develop a knack for it, I'm sure. Kudos and best of luck with the necessary evils.