I've honestly found squeezing your butt, and getting a SLIGHT lean by thrusting your hips forward (NOT bending at your thoracic spine) will give you the largest press. This is for strength, and not "superhero gymbrah shoulders". Ironically, it seems most people who perform lifts so 'correctly' never actually grow, because of overly meticulous form, causing an imploding effect resulting in.....no gain jeffrey.
As for arm position, not too far up with the elbows, and of course, avoiding your arms aiming away from you. It's a simple movement. Over-analyzed. I won't write a dissertation, so try to find a way to get the most weight overhead strict, and you'll get stronger and bigger.