I baste (long machine stitch or long zigzag stitch) about 1/8 inch from the cut edge of the quilt to hold the three layers together before applying the binding.
I use a wider finished binding (about 1/2 inch) because I like the look of it.
Also, because when I have the presser foot even with the edge and the needle at the left-most position, that's what it ends up to be. I think it's a lot easier to handle than a skinny little binding.
I also cut the binding on the bias - and I baste those edges together (I do pin them first about every six inches or so) - making sure that it's laying smoothly.
I also do a bit of practice binding with scraps to make sure it comes out the way I want it to. My first estimate at width is six times the finished width plus 1/8 inch. I usually have to try a couple of times to get it more precise.