OS, try learning the E and A strings inside and out. Again easy since at the 5th fret you should already know the notes A an D fall under your fingers from the E and A barre chord forms. Think of these as roots for major scales. There will be 4 silly-easy major scales under you fingers at each fret, as will be the pentatonic scale, the blues scale and the be-bop scale and others.

Armed with these learn the relative minors and you're off to the races. There will be very little popular music that you can't play doing the above.

Players don't compose hard stuff on purpose. If the part requires you to make nasty stretches or impossible grips chances are you're in the wrong position. If it doesn't feel natural when you play it that's a huge sign that you need to make an adjustment.

Hopefully what this will show is how applied theory greatly simplifies the act of playing guitar and makes it a lot more fun and easier.