Keep changing your mindset, to throw the other player off. The key is control, but you get control when the other player is confused. Whatever you're doing, do it for a handful of hands and then change up.
It's like what Jim Palmer said about pitching. "Hitting is the art of timing, and pitching is the art of disrupting the hitter's timing." Change speeds, change your pattern. Keep the ball low for a while, then start coming up high.
I let the cards set my first pattern, and then switch it up once I think the pattern has emerged. The last time I won a heads-up, I started with garbage cards, and kept folding my big blind and folding raises. Then when I started raising and reraising, it threw the guy off. Then I started to just call from the BB. So he figured this was weak, raised, and I came over the top.
But, I think one of the universal principles is to win hands with good cards, bluff with crap cards, try to see some streets with mediocre cards. And since you only have one player, slooooow play those pocket rockets and pocket kings.