50nl heads-up

just a quick updated. took a shot at 50nl hu(i'm a little underrolled for 50nl after running bad/playing bad recently..countdown to busto?ldo). hu has many advantages over FR and 6max(rake being one of them) but probably i still suck at hu so i have to proceed cautiously.
here are 2 hands that made me think:


$0.25/$0.5 No Limit Holdem
2 players

Stacks:

BTN	tukas	($54.75)
BB	Hero	($50.75)

Pre-flop: ($0.75, 2 players) Hero is BB

tukas raises to $1.50, Hero calls $1

Flop: ($3, 2 players)
Hero checks, tukas bets $2.50, Hero calls $2.50

Turn: ($8, 2 players)
Hero checks, tukas bets $5.50, Hero calls $5.50

River: ($19, 2 players)
Hero checks, tukas checks

Final Pot: $19
tukas shows:
Hero shows:

Hero wins $18.50 ( won +$9 )
tukas lost -$9.50

fold on turn? check river? if he bets river shall i call?


$0.25/$0.5 No Limit Holdem
2 players

Stacks:

BTN	Hero	($59.75)
BB	tukas	($45.25)

Pre-flop: ($0.75, 2 players) Hero is BTN

Hero raises to $1.50, tukas raises to $4.50, Hero raises to $12, tukas calls $7.50

Flop: ($24, 2 players)
tukas checks, Hero bets $15, tukas folds

Final Pot: $24

Hero wins $38.50 ( won +$11.50 )
tukas lost -$12

4-bet size? should i have checked the flop to induce a bluff?
hm..