I’m not a TPE pro; however, I’ve had a lot of success with heads-up play, and can tell you that most people are doing it wrong.  In theory, heads-up play should be the easiest form of poker ot learn because there is only 1 opponent.  In reality, most people don’t adjust sufficiently and some people adjust too much.  You can raise from the button with any two cards as the positional advantage is more significant than the cards you hold.  Out of position you should call with any hand that is in the top 50% of preflop starting hands (Q8o+).  You should 3 bet any hand that is in the top 25% of starting hands (any pair, any ace, K10+, QJ+).  Where I got these percentages should be obvious, if you only have one opponent who is raising with any two cards, any hand that is a top 50% hand figures to be ahead of his range.  Moreover, any top 25% hand is going ot be above the median of his range, even if he is playing the top 50%.  One thing to keep in mind though is that you are allowed to fold.  For a lot of people HU play becomes very rote because they ALWAYS min-raise the button and ALWAYS call out of position.  You don’t really gain an advantage by simply mechanically doing this.  Depending on the blind structure at that point, and how deep you are, it can be ok to fold low, unsuited, unconnected hands such as 83o, 72o.  This is obvious but high cards have a lot more value HU and suited/connectedness matter much less.  Post-flop you just have to play percentages and ranges.  If your opponent didn’t start out with a pair, he will only hit a pair on the flop 1/3 of the time, meaning if you were ahead preflop you are likely ahead post-flop.  It’s hard to make a pair HU.  You can probably bet Ace high or even King high for value if you think your opponent started off behind.  On the other hand, you really have to pay attention to bet sizing, and try to win more with your good hands, and lose the minimum with your bad hands.  Don’t always assume your opponent has nothing just because it is HU.  I’ve seen players call very large bets on the river with just Ace high when all they could beat was a bluff and they lose to big hands.  Finally, HU takes a lot of courage.  It’s like a game of chicken where the player who blinks first (folds) usually loses.  Don’t be the player to blink first. 

It takes a lot of courage but also control to play heads up.  You have to ride the cliff of being a maniac without ever driving completely off the cliff.  Some people aren’'t comfortable with this and some people just completely drive the car off the cliff.  I have no idea what your specific leak is but this is just good general advice.