Are there any techniques that a girl can learn to achieve orgasm?

Yes: Primary anorgasmia (never had one) vs secondary anorgasmia (stopped having them) is important. Change in hormones, low hormones, bad technique, a hooded clitoris, stress, inhibition and many other things may be causing the problem. Most women have their first orgasm via masturbation. If that is not working either, then its time to get help from your family doc. This can be fixed most of the time!