You want to win a big pot with your big hands. To do this you have to build the pot before any cards come along to either scare your opponent or give him the best hand. If he hasn't got anything he's not going to play a big pot no matter what you do. Make the pot as big as possible the times he has got something, and don't let him catch up cheaply. (Which is exactly what the other guys said, really.)

And my best piece of advice: step back down to 10NL until you have 500$. You said you know that you shouldn't play 25NL, and you're right. So just don't do it!