Les Black did a demo for us on Celtic knots. I haven't done one it probably 15 years and learned a lot from Les who is a very good woodworker. I went home and tried a bunch the way I first learned and then tried Les's technique. His was the easiest. Using Les's method you cut almost all the way through the board leaving a sort of hinge to keep things aligned. Then you add glue and sled the contrasting wood in. It can be a little difficult to get the wood to seat all way because the glue want's to hold it. Other than that it works great.
the method I learned was to cut all the way through and use a jig to keep things aligned. It's very easy to let things slip when clamping and in 2 cases actually slipped after I clamped and left the room. That sucked.
Anyway here are few of my good ones. I found that if the hinge is too thin it's easy to push the wood out of alignment when you clamp.