buy a metronome, that monotonous ticking is the key to it all. Steve Vai himself said "the key to playing really fast, is playing really REALLY slow".
basically, practice your scales (once you know your scales, and more importantly, what makes the scale) you can build an infinate ammount of chords from it. practice them as slow as you need to be able to play each note perfectly, then speed it up. if you speed it up to the point where you're playing sloppy, or missing more than 1 note per octave, then slow down a bit more until you can hammer them out at that speed, rinse repeat.
it's a long, slow process, i'm not going to lie it can be boring as ****. but get it down and you can play anything. learning scales also builds your "musical ear", so you can start listening to a song and playing along with it just on pitch.
if you want to buy any books, i would reccomend this:
http://www.amazon.com/Metal-Lead-Guitar-Primer-Stetina/dp/079351097X
followed by books 1 and 2.
i started out with just book 1, but i've found teaching people is easier with the primer, as it starts on a much more basic level, and builds a very firm foundation to work from. it has a CD with a tuning track (in case you don't own a tuner). in primer, you have about 2 chapters of exercises, then a short demo track with a solo to play along to. then another 2 chapters and a harder track to jam to.
book 1 builds your theoretical knowledge, along with more complex scale patterns (primer uses the pentatonic, which is quite basic, but very good for simple solos (see metallica. lol @ brackets in brackets), and building picking speed), and jamming tracks.
book 2 is gnarly.
then there's a final book "speed mechanics for lead guitar" which teaches **** like "The Flight Of The BumbleBee"....yeah....
good luck, like i said, if you have questions, post them.
i might have to start a guitar lesson thread