Alternating picking is something that can take years of practice to master, there are many different exercises to help develop this technique. Always try to use minimum movement for maximum effect. When choosing a pick other wise known as a "Plectrum" there are a few things to consider. The thinner picks emphasize treble more than bass. A thicker pick may offer more control when picking fast. It really is a personal preference, try a few and see what works best for you. In order for you to alternate pick like some of the great guitarist in the world you will need to put some real time into this. I recommend practicing the below exercises using a metronome and as you get better increase the speed. Always maintain clean picking you do not want to be sloppy, give it time don't be in a hurry practice will get you to where you want to be. When practicing the below guitar licks try counting (one, two, three, one two, three, repeat) They are called triplets.

Here are three alternate picking exercises, have fun and practice these and very soon you will be shredding on your guitar!

Alternate Picking 1

Alternate Picking 2

Alternate Picking 3