Read the article in the, mmmmm, article section on changing gears. You need to have played for a while and played a quite a few HU matches to nurture your skills but this is how you win playing HU. You can quite easily change from aggresser to tight if you have the skill and guts to do it.
When the blinds r low you can be as aggressive as you like but you will get caught and lose most of your stack. I play it tight early then when the blinds go up you can change gears and hit your opponent with bigger hands.
If I get a real aggressive player, most of the time you can slow play and they beat themselves