Bollocks. I just re-read your thread topic and realised I've misunderstood your question. May aswell share the post anyway to those who need help in learning alternate picking
Get some riffs you already know, and transpose them so they're played on only one string.
Original post was this (sorry if any aspects are patronising, I misunderstood your original message).
The best excercise style for learning and developing alternate picking (in my opinion from my experiences) is to use scales and pedalling.
A good example of one I used to use is to play is A harmonic minor only on the e string (and the others etc) with a pedal tone of the open e between each note, like this:
Code:
e--0-4-0-5-0-7-0-5-0-8-0-7-0-5-0-4
And use consistent down then up strokes. At first it's probably best to learn alternate picking on a fretted excercise, as the change in intonation between an open string and a fretted string is noticeable. However, due to the more difficult nature of using opens, your technique should develop faster.
Be sure to use a metronome, aim for accuracy and minimalised hand movements, in both the fretting hand and the picking hand.
Aswell as this, practice the actual down and up strokes. A good example that has recently helped me (with upstroke technique) is to learn riffs liek this one from Viking Kong (Racer X)
Code:
e-3-------5------6-----5------3
b---3-------3------3-----3------3
g-----3-------3------3-----3------3
d-------------------------------------5
x
Work on the following aspects:
*Having a neat and cleanly defined tone in both updtrokes and downstrokes
*Be sure the clarity and spacial orientation is even, between the upstrokes and downstrokes; this will allow for a consistent sound - if your upstroke tone is weaker than the downstroke etc, it'll show (an analogy to this is double bass with two different bass drums, as oppose to both beaters producing the same note.)
*Hand position on the bridge. I use a floyd rose system, whereby I use the bridge as a mild hand-set.
*Pick position - The string's tensile strength differs. you'll notice it's more resitant (bends less) closer to the bridge, and is 'looser' towards the neck. I play roughly between the pickups (which allows for good access to pinch harmonics). Play around and find where feels the most comfortable to play.
*The pick you use - Ditch any thin strumming picks, and lkook itno trying a variety of plectrums to see which suits you best, for string resistance and ease of playing.
*Pickmovement - I forget what the 'text book method' is for picking, but use small movements from the wrist; don't pick with your elbow or just with your fingers.
Sorry for the long post... I remember asking this question, to which people relied only "practice". Hopefully my response will help steer you in the right direction.