Slip-stitch edging (AKA chain selvedge) can make sewing-up or picking up stitches along an edge easier. You get one "chain" per two rows.
One way to do it is to knit the first stitch through the back. Slip the last stitch purlwise with yarn in front.
The way I do it is to slip the first stitch of every row purlwise with yarn in front, and knit the last stitch of every row, even if it was meant to be purled. This doesn't leave a garter-stitch border, but sort of pulls the edge stitches around to the sides, so they're facing outwards ready to be picked or sewn up. --Kake