[Guitar Slim II]

Typically, you would learn just a couple of open-position scales: Em/G pentatonic, C maj, A min. Remember, the major and minor are just the "set" of all notes in that key in the 1st position. No sharps of flats in C or Am, so if you know your notes, you shouldn't even need a fingering chart for them.

Then, you "CAGE" 'em up, so to speak, learn a few closed-position movable patterns, one or two octaves only, and learn how to track them by the root/tonic note. DO NOT waste your time memorizing every note of every scale and mode all up and down the neck.

I recommend learning just one or two closed-position patterns for the pentatonics -- the one based on Em/G (aka, Box 1), and the one based on Am/C. Then learn a closed major pattern that starts on the 6th string, and one that starts on the 5th. Remember, these do double duty as natural minor scales, and if you know how it works, you can alter them on the fly to create harmonic and even melodic minor.

At this point, were I your teacher, I would ask you: what exactly are you using these scales for? Are you actually applying them to the music you are playing? Are you analyzing the tunes you play to discover how they "plug in" to the scales and keys you already know? Are you trying to compose music using these scales and modes? If not, then putting the scales to work is definitely the next step.

Why? Because other than certain highly virtuoso styles, you're rarely going to hear a good guitar player play a straight up-and-down two octave scale. Scales are just the building blocks for melodies, licks and riffs. They change direction, jump around, use ornaments and articulations and bends, etc. Best to think of them as part of the key, and fitting into your chords. This approach applies to the simplest of music as well as the most complex, and is the best way to understand how scales work.

Get a few basic scales under your belt, and then start studying/learning solos and riffs to understand how they actually work in music. And I'll let you in on a secret: most of the time, it ain't that complicated. A few basic ones is all you really need. Lots of players know the basic patterns and can play very well, but have no idea what key they're in or what mode they're playing.

So, keep noodling, and start listening, analyzing, and stealing as many licks as you can.

A note on modes: I guess it depends on what kind of music you're playing. In most roots-based styles, dorian and mixolydian are the most common. Jazz -- you're on your own I'm afraid. But I'd get a solid handle on major, minor and penta first. Tackle dorian when you play your first Santa tune....