Thank you all for your support.
Just as an example about how to read an opponent, let me resume how I beat my opponent on heads-up.
Neither her nor I was willing to risk chips upfront in a duel. If she raised high pre-flop and I had anything save a handgroup 1 or 2, I would fold. If I raised, she would fold. So, I had to use my head to trap her if I wanted to win.
I noticed that she would usually only call pre-flop when she had the SB, letting me see the flop either for free (with the BB) or cheaply. IMHO that was a tactical blunder. Given that she dominated me 3-to-1 chip-wise, it allowed me to see more hands that I should have given my position. As the blinds were quite low (250/500 + 50 ante) she basically allowed me to pick and choose my hands. She had the chip advantage and could have wanted to choke me to death if she had wanted.
I thought perhaps she was on tilt, by that I mean that she was so afraid to lose her advantage that she was unwilling to use it. She was waiting for a way to pull me out cheaply, bidding her time at the expense of letting me choose my cards. She had time to observe me before reaching heads-up and could have concluded (with some reason) that I was a rock.
So I used reverse psychology to lure her in.
I waited until a I had at least a Group 4 hand and checked or called my way to a flop. Usually she would check as well, allowing the flop at a rebate. If I was sure I had a good chance of either having or gaining the nuts on the flop I would
check to lure her into a raise. I would call that semi-sandbagging.
When she had a playable hand, I abserved that she would usually raise either on the turn or the river. Rarely on the flop itself. Reading what I had and what she could have been holding, only then I would check-raise through the roof or go all-in. That put her into a dilemma, as she was faced between losing a few thousand chips for nothing or calling and risk to lose it all. In the end she called two of my all-ins. And twice she lost the showdown, the second time saying that she thought I was bluffing. Nope, I had a double AT with a fourflush draw while she had only QQ with a 8 as kicker. So in the end I was the one to suck her chips like Count Dracula in a blood bank.
The moral of the story is: even if you are heavily dominated and your chips go dry, you may never know what weapons future hands might give you to win. And if you lose, well being 2nd gives a nice profit on your buy-in.