The way I have always practiced to get better at guitar is just do normal scales, and keep in time with a metronome. After awhile you speed it up, and keep doing it until u can hardly play it good anymore, than practice at that speed till you can. After that I try playing music with strange/hard fingerings and practice those kind of things till i get good at them also. I guess all I basically do is find my limit at something, go a bit above it and practice like that till i can handle it, and then repeat.