Learn Texas Holdem

Question: Awesome site, just one question. A problem I seem to be having when I play hold'em is that I am chip leader by a lot, but then somehow it always seems my chips disappear, as was the case in the last tournament I played with my friends. I know the basic rules of what the chip leader should do, like being aggressive and betting a lot. But it seems that everytime I do this, I eventually lose all my chips. I'm not raising with any 2 cards, and I don't think I'm doing anything else really stupid. Also, my friends hate raising the blinds, especially if they're low stack, even if we all agreed before the tourney to raise them every 1/2 hour or so. So I look like a dumbass trying to tell them to raise the blinds over and over, and they refuse to and go "oh, stop complaining, look at you're stack." I guess I'm just wondering if you have any advice how to play when you're the chip leader, and sometimes how to play when the blinds aren't as big of factor as they should be. Thanks.