The only way to learn scales, that I know is repetition. So you look up a scale, then you practice it until you remember it by heart. I would only learn one scale at a time though, because if you try to learn to many at once you'll get them mixed up. The real fun with scales come when you know them, and improvise over music with them. Some scales you should learn besides major and minor include blues, pentatonic, modes, and there are lots more. Good luck!