Alternate picking is a form of picking used by many different types of music genres. It is what helps you play more notes with less use of your hand therefore sparing it of a lot of pain once you get this down!
To start off
To alternate pick choose a string. I suggest the E or the High E string for starters. You want to start with your traditional down stroke and then move back up on the same string so it's basically a down and up movement on a chosen string.
Use this for a easy practice:
E|--------------------------------3-4-5---------------------------
B|--------------------------3-4-5-------5-4-3---------------------
G|--------------------3-4-5-------------------3-2-1---------------
D|--------------3-4-5-------------------------------1-2-3---------
A|-------3-4-5--------------------------------------------3-4-5---
E|3-4-5---------------------------------------------------------7-
This is a beginner intro to alternate picking so that was very basic! Use it to make your own melodies and practices!
Oh yeah try using a metronome to help you build up speed! Try starting at something slow like 50 bpm for starters!
I hope I helped those of you who are just starting to alternate pick!