I don't remember when I learned to finish the binding so that it appears 'seamless.' But the method I learned has stuck. For some reason, it makes sense to me. I've tried other methods, some of them with fewer steps, some with more, and I always come back to my old stand by.
Here's how it goes.
1. After trimming the batting and backing even with the quilted top, sew the binding 1/4" from the edge of the quilt, leaving about 24" of the binding unsewn, that's at least 12" of 'unattached' binding on each end. Place the unbound section of the quilt flat on your work table. Lay the binding ends evenly along the raw edge of the quilt and fold the binding back on itself so the folds meet and 'kiss.'
2. Make two marks on the top binding layer one half the width of the binding from the fold. In other words, I've cut my binding strips 2-1/4", so one half of that is 1-1/8". I have two lines on the binding, each 1-1/8" away from the fold. Let's say you cut your binding strips 2-1/2" wide, then half of that is 1-1/4" - half of a 3-1/2" binding is 1-3/4" - half of a 4" binding is 2" - works for any binding width.
3. Fold the quilt onto itself, and pin the quilt layers creating some slack allowing you to work with the binding ends easier.
4. Bring the binding end from the left above the quilt onto the work table and open the fold. Place the binding so you can see the marking line, right side up.
5. Open the crease, and fold the right binding end, wrong sides together, at the marking line,
6. Then place the fold from the right binding aligned with edge of the left binding. At the same time, align the marking on the left binding with edge of the right binding.
7. Open the right binding fold, then draw a line, parallel to the quilt top, from edge to edge as shown. Secure the binding with pins on both sides of the drawn line.
8. Sew on the line.
9. Trim about 1/4" away from sewing (un-pin the quilt to test it first, if you like!)
10. Pin and sew to quilt edge.
Whatever method you choose to create a 'seamless' continuous binding, you'll never have a 'lumpy' edge again!
Bound to quilt!