1.) Buy "Speed Mechanics for Lead Guitar." Really, especially considering it's like $19 or something, it's one of those books anyone interested in technique needs to own.
2.) I wrote up a lesson with a ton of chromatic-inspired drills ages ago - I should probably dump it into PowerTab and get it up on this site.
(actually, just googled it - Speed Mechanics is $13.57 on Amazon. Go buy it.)
Speed mechanics is a very good book in which you can go through step by step, almost like a course.
First, play all these exercises to a metronome!!!
There are many things that you can do though, starting with the chromatics...
The 1-2-3-4 ascending the strings and 4-3-2-1 descending the strings is a useful exercise, but be careful. It is about the least useful for a couple of reasons:
First, I rarely use four finger per string scales in real music (sorry Cooley :lol

.
Second, this exercise will get you good at crossing strings with downpicks, but what does it do for up-picking?
So when I practice this exercise, I do it the normal way, and then a host of other ways as well.
e.g. if I am doing the 1-2-3-4 ascending and 4-3-2-1 descending, I will work on it for 5 minutes (this is very important) starting with downstrokes, then I will switch to upstrokes, i.e. up down up down (next string) up down up down.
After 5 minutes of that I switch the order of the notes so that I am descending notes when ascending strings, and vice-verse a la:
--------------------
----------4-3-2-1---
-4-3-2-1------------
etc. and down
---1-2-3-4-------------------
------------1-2-3-4----------
-----------------------------
Yeah I only have a 3 string guitar :rofl:
Then as I am sure you could have guessed, after that 5 minutes has passed I repeat the exercise starting with upstrokes.
From here I would progress to 1-2-4, 1-3-4, 1-3-5 (with second finger on 3), 1-3-5 (with 3rd finger on 3) exercises in triplet fashion. 5 minutes on each!
I would then play the triplet exercises and throw in string skipping. First just one string, then two, then 3, all the way to 6 (only works if you play a 7).
Then, finally, one last drill before I start playing diatonic. This is a drill I designed to get myself (and my students) to stop subdividing the beat based on how many note I am playing per string. Ex. triplets when playing 3 notes per string, and 16th/8th notes for 4 notes per string. Bad habit :noplease:
---------------------------1-3-4-
------------------1-2-3-4--------
-----------1-3-4-----------------
--1-2-3-4------------------------
This exercise will switch from working on inside picking to outside picking on its own!
There are two ways to play this:
1) All triplets
2) All 16ths
This idea will get you to learn to count a strong beat, even if it isn't on the first note of the string.
Okay, now I usually go diatonic in a specific key and play patterns in every position of the key, which is simple enough. This is more of an exercise in fretboard memorization. I'll do a different one every day, usually progressing through the cycle of 4ths.
After this, I will take some things that I have trouble with, and do a burst drill with them.
Example: Say you have trouble connecting 16th note triplet patterns ascending, a la: (beats in parenthesis)
(3)/////////////////(4)////////////////////(1)
----------------------------10-12-13-12---
------------------10-11-13---------------
---------9-10-12-------------------------
8-10-12----------------------------------
------------------------------------------
------------------------------------------
I would start my metronome slowly, so that it is rather easy to play. Then I would follow this rhythmic pattern. 1, 2, play riff, rest, 2, 3, 4, 1, 2, play riff, rest, 2 ,3, 4.
Where the riff starts on 3 and ends the first beat of 1.
I would gradually speed the metronome up as fast as I could play this.
However, you do NOT focus on playing this cleanly. What needs to be focused on is relaxing. When resting between the riffs, take your hands off the guitar and let them hang and "drip" all of the tension out.
The point of this exercise is to increase how quickly you can play relaxed.
Those are just some starters, there is a lot more you can do but I will let you digest that first
Good luck!