I put the BB on a small pocket pair here. Wrongly, but that was my instinct.

Anyway, despite being wrong about that, I semibluffed the flop trying to represent a 4, then tried to look very weak when I hit the flush. I thought my flush was good, but if I got raised or bet-into big by someone with a bigger flush, or if another spade came I'd re-evaluate.

Anyway, of course I didn't like the river but with that kind of bet I thought maybe he may have hit a set of twos, which would fit in with my read and make my hand good..

How could I have played it better?

PokerStars No-Limit Hold'em, $0.50 BB (8 handed)

saw flop|saw showdown

SB ($58.90)
BB ($51.10)
UTG ($38.50)
UTG+1 ($126.90)
MP1 ($35.25)
MP2 ($54.25)
Hero ($78.20)
Button ($47.70)

Preflop: Hero is CO with , .
UTG calls $0.50, 1 fold, MP1 calls $0.50, 1 fold, Hero calls $0.50, 1 fold, SB completes, BB checks.

Flop: ($2.50) , , (5 players)
SB checks, BB bets $0.5, UTG folds, MP1 folds, Hero raises to $2, SB calls $2, BB calls $1.50.

Turn: ($8.50) (3 players)
SB checks, BB checks, Hero bets $4, SB calls $4, BB folds.

River: ($16.50) (2 players)
SB bets $5, Hero calls $5.

Final Pot: $26.50

Results in white below:
SB has 4h 2c (full house, fours full of twos).
Hero has Qs Js (flush, queen high).
Outcome: SB wins $26.50.

I don't like it all especially against the small blind. After the flop you should be done or trying even harder to get a cheap showdown. Doubled paired boards really negate the power of a flush after being called on two streets. Single paired board I can see your actions as a lot more valid.

If you had got frisky and raised it up preflop I might like your play a little more against the SB as he would probably hold something like 77 more than a hand with a 4 unless he decided to call with 45 or A4h.

If I make a semibluff for the pot on the flop and then hit it - you're saying I should then give it up? My hand was good against someone holding a 4 on the turn..

I really thought I'd just gotten unlucky with that river double-pairing and decided to call because it was so cheap and I might still be ahead..

Can you explain a little further? I don't understand the bit 'after the flop you should be done', because I had then made what I had thought to be the best hand, I guess.

First off, when I raise, I raise it more but it is the bb so depending on what I thought of him, leading out for the min from the bb on a small paired board is fishy so I might just call because if I am drawing on a paired board, I want it to be cheap. If I raise, I make it $3, not $2. On the turn, I don't act weak because you should bet the same when you are strong and weak so no one can tell, IMO so I would bet more on the turn, at least 6. The river the way you played it, I still fold that getting more than 4:1 I am so sure I am beat he would have to be about $2 there for me to make that crying call. You may or may not have lost more money than me on this hand.