I have played this game a couple of times through and still can't learn..

I'm almost positive your talking about the two elderly masters Jian the Iron Fist and Mistress Vo, it's not too hard to stay to one alignment if you know how to talk to people according to whether you want to be open palm or closed fist.
If you want o be open palm try to stay out of as many fights as possible without resorting to violence do needless tasks to help people out and be kind and supportive to others. If you choose to be be closed fist however you should do the exact opposite.
Oh and just to be clear you do not have to be full open palm or closed fist to be able to learn these techniques just about a quarter of the way from the top.

The special martial art technique you get in Tiens Landing can be obtained by being either extremely good (Open Palm) or extremely bad (Closed Fist).

Being extremely good is easy. From the beginning, be nice to the students you defeat. Always try to go the extra mile in helping out in quests. Like not buying cheap medicine or helping out the old man in debt.
Being extremely evil is harder. Just do the opposite of what a good guy would do. Insult people, pick fights, and so on.

If you haven't earned enough good/evil points, future quests like in the flooded city and at the cannibal inn will provide opportunites to earn good/evil points, depending on your response/course of action. Usually the first option in dialogue is good, whilst the last one is bad. Then, once you have enough points, you can return to Tiens Landing.