This is my favorite tip for binding. I haven't seen it in any of the books I have so I don't know if everyone already does this, but I learned it in a class and love it.
This is for when you are machine sewing the front side of your binding to the quilt. Before you begin fold over the beginning of the binding to create a clean edge and press it down. Then line up the raw edge of the quilt with the raw edge binding as you normally would. Right sides of the fabric together. Pull back the top layer and sew down the bottom layer a couple inches in. I usually go about 4 inches in. Here's a photo of what I'm talking about.
My apologies, the next photo looked okay in the camera but is a bit blurry. :( Cut your threads and fold back that top layer of binding. Start sewing on top of both layers where you left off sewing the bottom layer.
Attach binding as you normally would for the rest of the quilt. When you return to your beginning point open up that binding again and tuck your binding end into the 'pocket'. Trim any excess binding so it fits in there nicely!
Pin it down and sew over all the layers until you get to where you began sewing on the top layer.
When you fold it over, this is what your binding will look like. You can tighten it up as you like.
I love this method because there is no math or measuring! And you get a clean binding each time.
