I went about it by looking at competition in my area, and charging more than the photographers that clearly didn't know what they were doing (there will ALWAYS be somebody willing to do it cheaper than you, and there will always be brides/couples looking to find the cheapest...I strongly recommend not targeting them as your clientele). I also don't feel that I can justify charging what some wedding photographers charge, especially if I view them as significantly better than me. I tried to price myself in the low end of what I consider the good photographers in my area. I started out at $750 USD, and have since upped that to $950, which I still consider probably a little lower than I probably should charge.
As a side note, I had a tough time deciding what to charge for "friends" who asked me to do their weddings. Originally, I felt I should give them a really low price, but at the same time, you are working, and they are hiring you, and thus far, I haven't had any of my "friends" scoff at my prices when they asked what I charged. If it's someone you're particularly close to, or someone you know can't financially swing it, well, of course you can come down some for them, or offer them something additional (a free engagement session, some free prints, etc). It appears (without me looking particularly in depth) that you at least somewhat know what you're doing, and if you price yourself low, you're doing yourself a disservice, as well as other photographers in the area that DO use wedding photography as their primary income.
Those are my thoughts...