If you memorize them while learning to pronounce them you're aided by muscle-memory. They are defined after how they are pronounced after all. The vowels are hard to explain but a tutor can show how to do them. That's how they've traditionally been taught, from mentor to student.
Take [ɑ]: relax the lips, open the mouth just about as far as it goes, try to press the tongue down, do not let the jaw move forwards, vocalize. A mentor can tell you when your mouth is in the right position. Once you've hit the right spot enough times, you've reprogrammed your hardware, and might be moving the mouth into position even when reading or thinking about IPA, which is fine :)