How much should i charge for my graphic designs?

I finished college for advertising/graphic design a couple years ago and then was working for an auction company doing all the advertising for their sales, I am now starting to design on the side but do not know how much to charge for my designs... i have a place that will print high quality for pretty cheap but i just dont know what is a reasonable price to charge ontop of the printing and shipping costs... i design websites (on wix.com), logo's, business cards, brochures, postcards, letterheads, and anything else requested... please let me know what you think is reasonable... i'm from ontario canada if that makes any difference...