Arms Should Be Straight
If yours aren't: Your pecs and lats are tight, and your traps are weak.
The fix: Loosen the lats and chest with foam rolling, and do chest-openers, such as standing with forearms against the edges of a door frame and leaning forward. Strengthen traps with Superman pose. (Lie facedown with arms extended above head; raise arms, head, and chest, then hold. Lower and repeat.)