With the method that I use, I cut a little of the fabric away, which reduces the bulk. This is my method (I hope it makes sense!)
You start by trimming the batting (wadding) level with the quilt top being careful not to cut the backing fabric.
Next you trim the backing fabric so that it is one inch larger than the quilt top and batting.
Now, at each corner you take a ruler and measure two inches down from the point of the corner on each side and make a small mark.
Fold the point of the corner onto the quilt top in a diagonal line between the two marks you have just made and press. (Please ignore that my corner tip has a cut made across it but I had cut it off before I decided to photograph it!)
Now fold the point of the corner back on itself so that the tip rests on the first fold you made and press again.
Unfold the corner and cut away the point along the second fold line, cutting away a small triangle of fabric.
When you have done this to each of the corners you are ready to fold the backing fabric which extends beyond the quilt on each side to make the self-binding. Fold the backing fabric in half towards the quilt top so that the raw edges of the quilt and the backing fabric touch. Press.
Fold the backing fabric in half again enclosing the raw edge of the quilt. Press and pin (or clip - my new binding clips were great!!) in place.
At the corners fold the cut point of the corner over the corner tip of the quilt top along the fold that you made earlier before double folding the backing fabric.
Then continue double folding the backing in place, first on one edge and then on the second edge to meet it.
This gives you a neat mitred corner with much less bulk.
When all the edges and corners have been pinned (clipped) in place simply top stitch the binding close to the inside folded edge.
When you get to the corners stitch over the mitre putting your needle down to turn.
Stitch all the way round and over stitch where you started to finish off and your quilt is finished!
Hope this is useful to someone!