Hey, ever looked at a piece of music and looked at the key signature and wondered why on earth people wrote music like this? Like, with key signatures and stuff?!?!?!
Well..... it all does end up making sense in the end. The best way to make sense of it all is called 'the circle of fifths'. Have a look at this link, then continue reading.
There's a pattern to both major and minor scales.
1. For every key signature, there is a major key and a minor key that use it. If you look at the linked picture, you'll see every possible key signature. You'll see the major key that goes with it on the outside, and the minor key that goes with it on the inside of the circle.
2. If you start at the top of the circle and go around clockwise, one sharp is added to every new key signature you see. After a while, it gets into a world of flats and then they begin to disappear as you keep going around. All the way around the circle, the corresponding major and minor keys go up in an interval of a fifth. So, if you want to know which major key has three sharps, just move around the circle from the top and you'll find out. One day, you won't need this picture to help you out because you'll do it all in your head.
3. I would suggest printing it out and colouring in every key signature so you can kinda memorise it better. Like, you could end up thinking, "yep, A flat major and F minor - I know those - they're the aqua ones."
4. Every single key signature in western music is here. Only twelve to learn........ (yay)