Let me show you one more photo of a past sew, the "Corpse Bride."
It's rather funny, because not only was I poking fun of the Tim Burton movie after it came out, but I made that costume the Halloween before my wedding. The next wedding dress I wore was a little more, um, elegant.
Really, I just free-handed the dress. Take an inexperienced sewer, no pattern, a pair of scissors, and extreme luck, and voila! It happened to fit. The top is a velvety fabric made into the main frame of the dress (you'll see the rest of it poking out of the bottom of the dress, on my legs), and the overlay of the skirt is a satin material. It was a great first sewn dress, because I didn't have to worry about hemming anything but the top, mainly because I had to thread elastic through it. Even the top of the skirt had ribbon sewn onto it. A great extra touch that can hide a multitude of errors. Seriously though, I think it actually looked half decent under there. I took the scissors and hacked away the bottom of the skirt to give it some wear-and-tear in the graveyard look.
Other than that, I only took a decorative comb-pin to secure the veil to the black wig. Fake pearls, off-white roses and black lipstick/nail polish give it that extra edge. A few kids were scared...poor dears. ;)