$55: How to practice folding?

[AA suited]

Hello. My name is AA Suited, and I have a problem folding 2pair and above.

ie:
lvl 3, ~same stacks, 4 people see flop. i'm sb and flop 2 pair on rainbow flop that's J high. (no reads)

i check, bb checks, mp checks, co checks.

flop = blank, but flush draw possible.
i check, bb checks, mp checks, co bets 1/2pot, i check/raise, bb folds, mp folds, co goes all in. i insta-call. co turns over a set. i lose

i NEED practice in folding!

Any suggestions on how to practice folding?