Everybody knows the warm-up exercise where you play 4 chromatic notes in sequence and move sequentially through each string without shifting positions up or down the neck:
Chromatic warm-up PDF ::: Guitar Pro 5
This is fine for developing basic coordination between your left and right hands, but it’s not exactly musical.
Life is short: if you’re going to spend time working on technical exercises, it makes more sense to design exercises that at least have some potential for musical application. Making an exercise more musical makes it more fun to play as well.
With some slight changes to the warm-up exercise above you can turn it into a true chromatic scale. This gives you both coordination practice AND the benefit of musical applicability:
Make sure that you stick to strict alternate picking, even on the slides — every note should be picked.
I encourage you to experiment with variations on this exercise — for example, playing it with a triplet feel instead of straight sixteenths. And make sure that NO MATTER WHAT you play it clean. If it’s sloppy, you’re playing too fast. Pay particular attention to fingers 2 and 3 — for me those tend to be the troublemakers.