A really simple and useful technique that adds a visual twist as well as possibly saving fabric.
Visually challenging, but simple to do, once you know how. When surrounding a square you can cut four pieces of fabric the same size, therefore saving fabric. This in turn can get you out of trouble and stretch the border fabric. It will save you possibly having a join or adding a bit.
This technique can be used to surround individual blocks; to create the block itself and also as a border technique.