Pick up & knit border, at corners

I’m assuming that if you pick up and knit a border around something square or rectangular, you need to do some increases at the corners so it will lie flat and not be bunchy-curl-uppy…is there a certain formula for this? Is there as better increase than others for this, like for something in garter stitch?

:thinking: You could either pick up and knit on two opposite sides and then do it again on the other two sides–the second two sides would include the added on edges of the first two sides. Not as pretty as mitered corners, but easier.

For mitered, I’ve read that you increase one stitch on each right side row in the stitch before the corner stitch.