I'd say if you're just looking to beef up you're theory a paysite would not be the best way to go.
Although I've never used one I reckon taking the old school approach and learning them shapes is a great place to start.
For example you mention, playing that ole a minor on the 5th aka shape one, so nailing the next four pentatonic shapes up the neck ought to open up youre playing quite a bit.
-hope this helps