‘Simple’ chests are easier than the ‘expensive’ looking ones, usually.
Doors vary, some are harder than others.
Find the sweet spot. It is easiest to pick if this is on a margin. You can back out of the picking and try again until you get a ‘nice’ bind. When you rotate it you have to be immediately following with the mouse, If the lock is too hard the size of the ‘sweet spot’ is low and the ‘noise’ on the cursor position is higher. It might help to ‘lead’ the spot slightly when starting.
Don’t use your last lock pick. Go and find another instead.
Perks help with some aspects of picking, as does practice on simple locks.