Advice on 4 person tourney

[newcool]

Hi, my friends and I play a 4 person tournament with $25 buy in and winner takes all. Dealer chooses games and the games are Texas Holdem, Omaha high, and High Chicago. Basically, I am looking for any advice on winning.

One guy likes to go all in every other hand. I tried to use this against him when I had pocket aces and he won with a flush. This always happens too!

Thanks for any help