Betting with draws.. line check

Villain is unknown..

PokerRoom No-Limit Hold'em, $0.25 BB (4 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Hero ($36.45)
UTG ($23.35)
Button ($17.85)
SB ($14.65)

Preflop: Hero is BB with 5http://www.flopturnriver.com/phpBB2/...es/diamond.gif, Ahttp://www.flopturnriver.com/phpBB2/...es/diamond.gif.
UTG calls $0.25, 1 fold, SB completes, Hero checks.

Flop: ($1) 6http://www.flopturnriver.com/phpBB2/...miles/club.gif, 4http://www.flopturnriver.com/phpBB2/...es/diamond.gif, Thttp://www.flopturnriver.com/phpBB2/...es/diamond.gif (3 players)
SB checks, Hero bets $0.5, UTG raises to $1, SB folds, Hero calls $0.50.

Turn: ($3) 7http://www.flopturnriver.com/phpBB2/...iles/spade.gif (2 players)
Hero bets $2, UTG calls $2.

River: ($7) 9http://www.flopturnriver.com/phpBB2/...miles/club.gif (2 players)
Hero bets $4

I let villain bet the turn? if he checks behind, no big deal...

I think on the turn and river you are only folding a bluff, which is not likely from the flop minraise.