In HU games, cards have more value. You can play alot more hands then usual. Try low pairs and suited connectors. If he raises everyime pre-flop you should at least call sometimes with decent hands to see the flop. If all low cards come out for you and you make a set, chances are you got him beat. And if you feel confident enough, you can re-raise him pre-flop and see where he stands, and he might just fold. Because there is no way he can get good cards everytime.