I'm not very experienced, but play a different scale every day, and after the practice, reward yourself by learning a song, or parts of it

makes guitar playing very fresh, not repetitive and boring, as it ought to be

oh and hardcore practicing won't do you much good either, make sure if you feel you've reached your limit, take a break and come back later. you'll find playing things with a relaxed mind much easier

the hardest part is probably sticking to that routine, I'm having trouble sitting down still to practice using the metronome.