The first thing you have to think about when you want to prepare your fabric for a quilt is do I wash it or do I not wash it? And there are lots of arguments for either side. Some people swear they wash everything and some people don't wash it at all. So you should figure out who's getting the quilt, what's it being used for? If it's intended for a baby, I would definitely wash the fabric first. You want to get out chemicals left in by the manufacturer. Also, it's going to get washed a lot if it's for a baby and you just want to make sure it's going to do any shrinking before you sew the pieces together.
Other than that, I myself, am in the non-wash camp, basically because I'm always in a hurry to start something, so I usually piece a quilt and worry about it later. You just have to be comfortable with taking a little risk. If I'm using really deeply-colored fabric, like red or purple, I might throw in something like a dye magnet when I wash the quilt for the first time. That is a product made to absorb loose dye and that helps a great deal.
I think the important thing is whatever you decide to do, wash or not wash before you cut, you have to be consistent. You don't want some of your fabric preshrunk and some shrinking after you've sewn them together. Then you're going to get puckers and ripples. So either wash everything or wash nothing until the end.