PokerStars - $3.32+$0.18|20/40 NL (2 max) - Holdem - 2 players
Hand converted by PokerTracker 4

Hero (SB): 29.8 BB
BB: 45.2 BB (VPIP: 73.02, PFR: 45.16, 3Bet Preflop: 7.41, Hands: 69)

Hero posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has Q J

Hero raises to 2 BB, BB calls 1 BB

Flop: (4 BB, 2 players) 9 T A
BB checks, Hero bets 2.65 BB, BB calls 2.65 BB

Turn: (9.3 BB, 2 players) 7
BB checks, Hero checks

River: (9.3 BB, 2 players) 6
BB checks

Villain has been folding to cbets 4/10. This river card is likely a scare card for Villain, but betting it really narrows my value range to flushes and a rare straight. Bluff or give up? I know I should've bet flop 1/2.

Now first of all you played the hand really standard until the flop.But I really dont understand the part you say I should have betted 1/2 flop!You mean that you always bet 1/2 flop in all boards or you bet bigger with your semi bluffs or pure air???You sound like you deviated from your original betting trategy right here.I dont think that villains in $3.50 husng's think if your range is balanced but you shouldn't deviate from what you originally do.Now the flop bet was really STD ,nothing to talk about that.
Play on the turn is marginal IMO.Most of the times I bet in these situations just because villains are calling with whatever on the flop and i really think that with your QJ here you have equity against 9x or Tx and you maybe dont have like 8 outs for your straight but 11-13 outs if a Q or j comes on the turn and river.If he called turn to my second barrel his range would really look like Ax and i would bet the river of course.Now i think that if you decide to bet the river you are getting snapped by a 9x or Tx or Ax and bluffing here i thonk is -EV.Just live to fight another day!Dont waste money!