Alright so villian raises 2BB PF, I have 88 in SB so I just call, I think that's standard? I flop my set and an A hits the rainbow board, which is great for me against his range, so I bet half pot, he calls. Turn comes a 6, no big deal imo, I lead for about 2/3 pot, he raises.....I'm thinking maybe he has 66, AA or 99(maybe slow-played AA/99 on the flop). I feel I'm good against most of his range(Ax hands, weird 2-pairs, weird micro-stake bluffs), so I 3-bet(not sure about 3-bet sizing I'm fairly bad with bet & raise sizings). River completes a flush draw, I feel like he would've just called the turn with a flush draw, so I just shove lol. Is there any spot I should've played differently?

PokerStars - $0.02 NL (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

MP: 176.5 BB (VPIP: 100.00, PFR: 28.57, 3Bet Preflop: 0.00, Hands: 7)
CO: 100 BB (VPIP: 26.53, PFR: 24.49, 3Bet Preflop: 15.79, Hands: 51)
BTN: 96 BB (VPIP: 14.29, PFR: 0.00, 3Bet Preflop: 0.00, Hands: 8)
Hero (SB): 100 BB
BB: 99.5 BB (VPIP: 16.67, PFR: 6.67, 3Bet Preflop: 0.00, Hands: 31)
UTG: 88 BB (VPIP: 17.43, PFR: 11.01, 3Bet Preflop: 2.50, Hands: 109)

Hero posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has 8 8

fold, MP raises to 2 BB, fold, fold, Hero calls 1.5 BB, fold

Flop: (5 BB, 2 players) 9 A 8
Hero bets 2.5 BB, MP calls 2.5 BB

Turn: (10 BB, 2 players) 6
Hero bets 6 BB, MP raises to 12 BB, Hero raises to 35 BB, MP calls 23 BB

River: (80 BB, 2 players) 4
Hero bets 60.5 BB and is all-in, MP calls 60.5 BB

I think c/r flop gets the money in more often but either way you just need to do whatever it takes to gii.

why do you donk the flop?

just c/r flop, if he has an A you're getting a good portion of his stack before the river