What I usually do (as I mentioned in another post) is that every 5k hands or so, I'll look on my main page to the hands I played. Print that list out.
Then look at two numbers:
VP$IP and BB/Hand.
In that context, VP$IP is the percentage of times you voluntarily played that hand. Look at CCPF (Cold Call Pre-Flop Raise--calling 2 bets cold), look at your PFR for each hand.
Find those hands that you're VP$IP'ing more than half the time, and that you're losing BB/Hand playing. These are your losing hands. On the main page, highlight one of the hands you found using the above criteria. All the individual hands you played with those starting hands will be displayed in the window below. Click on the hand number to see the history or highlight the hand and press the "R" button to replay it. Think of how you'd play it differently now, in retrospect. Post some of the ghastly ones or the ones you get stuck on in the Limit forum. Ask for others' opinions.
YMMV, but that's how I find my leaks.
Look on my blog (address in sig below) for the post "The Biggest Loser (Internet Poker Version)" for my analysis just this week on the hands that suck for me. Good luck!