I thought about betting flop but decided to check, V checks behind, I think he would bet his best hands here so I think he can have some weaker PP's, weak top pairs, etc. OTT I check and villain bets small, 1/3 pot. How do we perceive this bet? thin value/protection? wouldn't he want to go larger to protect vs flush-draws with a weak top pair or good middle pair etc? and if we think he's betting for thin value on the turn is the river a good card to bluff, bet fairly big or over-bet on?

PokerStars, Hold'em No Limit - $0.01/$0.02 - 4 players
Hand delivered by Upswing Poker

UTG: $4.52 (226 bb)
BU: $2.24 (112 bb)
SB (Hero): $2.00 (100 bb)
BB: $1.18 (59 bb)

Pre-Flop: ($0.03) Hero is SB with Q♥ A♦
UTG raises to $0.06, 1 fold, Hero 3-bets to $0.24, 1 fold, UTG calls $0.18

Flop: ($0.50) 2♦ 7♥ 9♦ (2 players)
Hero checks, UTG checks

Turn: ($0.50) 3♥ (2 players)
Hero checks, UTG bets $0.16, Hero calls $0.16

River: ($0.82) K♣ (2 players)
Hero checks, UTG checks

Total pot: $0.82 (Rake: $0.03)

Showdown:
UTG shows 4♠ 4♣ (a pair of Fours)
(Equity - Pre-Flop: 55%, Flop: 72%, Turn: 86%, River: 100%)

SB (Hero) shows Q♥ A♦ (high card, Ace)
(Equity - Pre-Flop: 45%, Flop: 28%, Turn: 14%, River: 0%)

UTG wins $0.79

Once he checks back flop just start bombing.

I agree with this. Same principle I take when IP. If I check back the flop, and they check turn again, I'll bet just about everything on the turn except my SDV that needs the least protection.

Where I struggle is not always knowing which rivers to keep bluffing.