I've been playing the 50k play money games on Poker Stars until I felt good enough to play for cash, and today I tried it and won US$22.50 . Actually, I think the people in the play money games were better, but maybe this was just a blip. Here were the turning point plays:

Play one - I'd been stealing a lot of pots on the bubble (there is no bubble in play money), so the villain decided to take a stand.

PokerStars No-Limit Hold'em Tourney, Big Blind is t150 (4 handed) FTR converter on zerodivide.cx

saw flop|saw showdown

SB (t3738)
BB (t3835)
UTG (t2162)
Silverfist (t3765)

Preflop: Silverfist is Button with Q, Q.
1 fold, Silverfist raises to t450, SB raises to t3738, 1 fold, Silverfist calls t3288.

Flop: (t7626) 8, 7, T (2 players)

Turn: (t7626) 7 (2 players)

River: (t7626) Q (2 players)

Final Pot: t7626
Main Pot: t7626 (t7626), between SB and Silverfist. > Pot won by Silverfist (t7626).

Results in white below:
SB has As Tc (two pair, tens and sevens).
Silverfist has Qd Qs (full house, queens full of sevens).
Outcome: Silverfist wins t7626.

Play 2 - Villain was pretty weak post-flop so I'd been stealing pots from him.

PokerStars No-Limit Hold'em Tourney, Big Blind is t200 (3 handed) FTR converter on zerodivide.cx

saw flop|saw showdown

Button (t3685)
SB (t3087)
Silverfist (t6728)

Preflop: Silverfist is BB with 6, K.
1 fold, SB completes, Silverfist checks.

Flop: (t400) A, 9, 3 (2 players)
SB checks, Silverfist bets t200, SB raises to t800, Silverfist calls t600.

Turn: (t2000) 2 (2 players)
SB bets t2087 (All-In), Silverfist calls t2087.

River: (t6174) J (2 players, 1 all-in)

Final Pot: t6174
Main Pot: t6174 (t6174), between SB and Silverfist. > Pot won by Silverfist (t6174).

Results in white below:
SB has Ah 7d (one pair, aces).
Silverfist has 6h Kh (flush, king high).
Outcome: Silverfist wins t6174.

Thanks to everyone for the advice on this forum. I still need to work on my post-flop play a bit, but you've all been very helpful.