No reading because I only recently played $25

PokerStars No-Limit Hold'em, $0.25 BB (9 handed) from (Format: FlopTurnRiver)

Button ($24.25)
Hero ($25.35)
BB ($19.30)
UTG ($9.30)
UTG+1 ($19.90)
MP1 ($29.10)
MP2 ($9.45)
MP3 ($15.50)
CO ($10.60)

Preflop: Hero is SB with K, A.
5 folds, CO calls $0.25, 1 fold, Hero raises to $1.25, BB calls $1, CO calls $1.

Flop: ($3.75) J, A, 9 (3 players)
Hero bets $3.75, BB raises to $7.5, CO folds, Hero ??

I fold here, this isn't a position I want to play a big pot in.

I would call. Why? You have the king of spades. If you call and a A, K or spades hits at the turn you are in very good shape and I would go all-in.

MHFlush

Well I decided to just call, the turn was a 5 of clubs, and I checked, he pushed. Call/Fold?

if you call the flop, you are stuck calling all in on the turn for the pot size. I often fold on the flop as there isn't much i'm beating or even in great shape against except AQ and AT.

Yeah, and to my surprise, he had AQ