1) I tend to go to the races pre-flop instead of playing tight and letting a hand go. While racing is often the right thing to do in a cash game, when the pot odds are right, it's rarely the best move in tournament play.
2) Post flop, I've been known to overvalue top pair/top kicker (TPTK, as the kids say on the street these days)
So yesterday afternoon, at my department's picnic, we're doing a charity hold 'em tournament for hurricane relief. We start with about 16 players, and blinds go up every five minutes (!). I'm playing tight, tight, tight, winning a grand total of one pot with pocket queens when the flop is all rags.
With six players left, I've got a stack of about 3x the big blind and there a huge stack sitting to my right. I'm under the gun with TT. I call, three players fold, and Nathan, on the small blind, pushes his stack all in. He's got just a little more than I do. The big stack thinks about it, hesitates, then tosses a few big chips in the stack to call him. I call him as well. Nathan's got me dead to rights with pocket aces. The big stack shows 8♣ 4♣. Naturally, no tens or aces hit, but the big stack gets an 8 on the flop and a 4 on the turn. Sigh.
So last night, I play the Happy Days midnight tournament (losing both BJ match plays, by the way), and I'm playing tight. With about 20 players left, I'm dealt 33 at UTG+1, and I fold them without even thinking about it (they'd have hit a set on the river; I wouldn't have stayed in that long). More tight play, and we're down to 14 players, blinds at $1000/$2000, and I'm dealt AQo in the big blind. I've got $5500 in chips left.
There's two callers, including the small blind, and the flop comes Q9Q. I check, intending to check-raise if anyone bets small. The next player checks, and the small blind comes in for $2000. I push my $3500 all in. The other player folds, and the small blind calls, showing KTo, for an inside straight draw. The turn's a harmless 4, but the jack falls on the river, and I go home, somewhere around 12th out of 42 players.
I only got involved in a handful of hands, and had the discipline to fold when I missed the flop. Limping with A9s on the button? Fold when the flop misses. QJo? Not even playable. I'm very happy with my play last night. I think I'll try again tonight and see if I can get into the cheese.