One of the most important things IMO is to MIX UP YOUR PLAY early. Picking up on your opponents betting/calling/raising patterns is paramount. Pay particular attention to his...make it as difficult as possible for him to do likewise.
Early in the match when the blinds are low is the time/place to change gears often. Alternate the hands you limp/raise with, lead/c-r with on the flop, etc. etc. Use this "cheap" time to cut of bluff attempts, occasionally calling down with less, raising hard occasionally his standard continuation bets, etc. While you don't want to dig yourself a hole too early...it is JUST as important that you create an image such that his 'standard' plays are constantly called into question.
As the blinds increase, so must your aggression. You'll find it a little easier to assert yourself later, when you've made the effort early to create the "formable+tricky" image. Of course when either of you get to the 10-15BB stage, you're done raising/calling PF...push,push,push.
There are some HU links in
this thread, but most apply to the end of a SnG, when the blinds have reached the push/call point. Not too useful for the start of your HU match, but worth reading for your end-game.
Good luck!