Shredding

master it slow so as you start to speed up with practice, you're not a sloppy player.

otherwise, just work on your picking and fingering technique. take your time, practice and if you start to get frustrated, take a break and come back to it.
 
synflower said:
master it slow so as you start to speed up with practice, you're not a sloppy player.

otherwise, just work on your picking and fingering technique. take your time, practice and if you start to get frustrated, take a break and come back to it.

Thats really good advice
 
Scales are a good place to start but you can go a lot further than just that. You might want to check out my site too. ;)
 
to improve speed you could just do chromatic exercises like -1-2-3-4- on the low E and moving up one string at a time till you reache the high E, then back down, then move up a fret (so its -2-3-4-5-) and do the same. you can go over the whole fretboard with this and there are countless variations of this, like using only 3 notes per string (try doing it with middle-finger, ringfinger and pinky...), string skipping, ..........................................
you can start slowly and get faster as you get comfortable with the speed
 
Yes, eventually the person needs to break the redundent scale and mix it up so that they're not locked into a single routine. If you're still learning your shouldn't be worrying about how fast you can do it.
 
If you want some good exercises check out the Hanon Books (Amazon).

A great reference book for scales / modes is the Guitar Grimoire.

I'm a keyboardist and have the keyboard grimoire and its a useful reference tool. Also get your self one of those $10 chord computers, they're also helpful.

Starting all your riffs out slow is what makes the difference, if you cant play the riff perfect slow dont expect it to sound good when you play it fast.

Another suggestion is when your in a rut just step away from your instrument, take a week or two off from it. In this break start listening to different music that you would normally listen to. You'll have a fresh outlook on things when you come back to your instrument.