Okay, so i've been asked to make two wedding cakes in december...it'll be my first time making a cake for a wedding...its for a friend's friend but business is business...however, i'm not quite sure how much i should charge...the first cake is for 300 people--with a lot of gumpaste work...and the second cake is for 500 people with a simple design....

any suggestions on how i should charge?

First and foremost you must be legal in order to sell cakes so hopefully you've got that covered Second you need to figure out how much it cost you to make a cake factor in all your cost including soap, elec., gas, water, trash, ect.
Decide how much you want to make an hour then you'll have an idea of what you can charge.
Then you have to price your gumpast decos as well I think most ppl so it by size and the amout of time it takes to make.

hth