how do you harmonize guitar leads and stuff? Is there a simple formula, or do you have to decide if you want like 3rd, 4th, 5ths, or whatever?
Pretty much, but they don't always just directly harmonize eachother. Look at the master of puppets harmonized part for instance- the parts sound good together, but the higher part is not the same as the lower one.
I'm not sure if you want a suggestion about who to listen to for more examples of harmonizing, but Iron Maiden has some amazing and great harmonized guitars on almost all of their songs. Definitely check them out for guitar harmonizing.
yeah, its just like ive been playing for awhile, i do most everything by ear, but with bands and stuff, i want to start learning more theory related stuff, so yeah, thanks guys!