Ok Ive been playing by ear since I was 6, never really learned music or theory and now I would like to

I see all kinds o crap on the web about scales this and that, but have no idea where to start, what to practice etc.

I think I understand the CAGED theory slightly, but my major question is this, when practicing scales...

1. What scales should I master first? Major? etc.
2. Anyone know of a good diagram?
3. Thanks in advance for all help :-)