I've tried doing this before, but I always end up in a confused mess. Is there a simple way to do this?
^it really is alot easier to memorize the notes on the fret board, memorize your scale intervals then just pick your key and scale and you're set!
Learn the notes on the fretboard, and learn the circle of 5ths.
http://www.all-guitar-chords.com has many scales written all across the fretboard. It'd be a help if there was one in particular that you needed to memorize quick
I would just recommend learning the notes in the scale instead of relying on patterns. Patterns aren't bad though, they help with on-the-spot sclae playing, but if you know the notes in the scale and the fretboard, you can make your own patterns on the guitar.