A few short weeks ago I would probably have lost a great deal of my chips on these hands, I feel that I am improving however, and here are two hands I would like some feedback on. Did I play these as well as i could have? Or was i just throwing away my chips with second best hands?

Hand 1
Party Poker No-Limit Hold'em Tourney, Big Blind is t200 (6 handed)

Button (t1630)
SB (t2648)
Hero (t4520)
UTG (t2346)
MP (t3476)
CO (t5380)

Preflop: Hero is BB with , .
2 folds, CO calls t200, 1 fold, SB completes, Hero checks.

Flop: (t600) , , (3 players)
SB checks, Hero bets t400, CO calls t400, SB folds.

Turn: (t1400) (2 players)
Hero bets t200, CO calls t200.

His call on the flop here tells me that he has me beat, probably with an ace and a better kicker. The last thing I want to do on the turn is bet and build a pot where Im a big underdog. However I have a straight draw and my aces could still be good, and if i check here I'm just inviting him to take a shot at me so i put in a small blocking bet.

River: (t1800) (2 players)
Hero checks, CO checks.

Final Pot: t1800

Results below:
Hero has 2c As (two pair, aces and threes).
CO has 9d Ah (two pair, aces and threes).
Outcome: CO wins t1800.

Hand 2
Party Poker No-Limit Hold'em Tourney, Big Blind is t400 (6 handed)

Button (t1330)
SB (t5896)
Hero (t3120)
UTG (t1746)
MP (t1528)
CO (t6380)

Preflop: Hero is BB with , .
4 folds, SB raises to t800, Hero calls t400.

With QTs I'm definately not folding to a min raise and a possible steal attempt.

Flop: (t1600) , , (2 players)
SB bets t400, Hero calls t400.

Looking back I think i should have folded here, however if he has flopped a flush then I think he would have slowplayed and let me try to take the pot away from him, If he hasnt flopped the flush then I'm drawing live to an open ended straight and I'm getting 5-1 odds.

Turn: (t2400) (2 players)
SB checks, Hero checks.


River: (t2400) (2 players)
SB checks, Hero checks.

Should I have bet here? His check on the turn could easily be a slowplay but a check on the river is far too risky for him if he has the flush and is relying on me trying to bluff.

Final Pot: t2400

Results below:
Hero has Ts Qs (two pair, tens and fives).
SB has Ad Jd (two pair, jacks and fives).
Outcome: SB wins t2400.

Thanks