Limit Holdem tourneys - Help - I can't close the deal!

[PFrese]

I have been playing holdem habitually for a while now, abd I have just started playing in tournaments. As in, one week ago! All at Paradise, $10 buy in. I am having a problem - winning! I can get down to the final two with regularity, but can not seem to close the deal. Out of 10 times, I have won 3 times and come in second 7 times. Several of my losses have been after I have been the chip leader x2. 2 of my wins have been because I was the chip leader x10 and simply had too big of a lead. So, my question is this - how do you WIN these things!!!! How does your strategy change when you are heads up at the final table?

To get there, I have been playing tight early, and then super agressive once the table is down to 5 or so. But, once it is down to two...

Thanks in advance,

PaulF