An even number of stitches.
Knit one set-up row.
Row 1 *K1, K1below (ie. knit into the stitch below the next stitch instead of into the next stitch itself)*
Row 2 Knit
Row 3 *K1below, K1*
Row 4 Knit
I usually add an extra knit stitch (at least) to each side to keep the edges neat.
This tends to turn up nowadays as a 2 colour pattern, rows 1 and 2 in colour A and rows 3 and 4 in colour B. This is a close-up of a lap quilt in two shades of blue merino wool.
It also works in more than 2 colours.
This is a close-up of a blanket in Twilleys Freedom Spirit 100% Wool. Every Row 1 and 2 is in the same green shade that has been used for the garter stitch edging. Each set of 3 groups of rows 3 and 4 is in a different contrast colour. This is a good way of using up left over yarn.
It also works very well in a single colour.
This raglan cardigan is 100% cashmere. The buttons are ones I make from Fimo (I find they wash perfectly).
I use a garter stich hem on the bottom of the body and the outer edge of the collar as I find both points are inclined to lie better that way. The sleeves don't seem to need any edging, but I keep the cuff end of the sleeve fairly tight as I use elbow crutches. For a wider cuff a garter stitch edging might be a good idea. I added elbow patches inside the sleeves (the same stitch but worked on a size smaller needle), and large pockets inside the fronts. I can't easily carry things about because of the elbow crutches, hence the pockets, and they are inside because outside pockets have been known to catch on things. As I have what used to be called a dowager's hump, now called a kyphosis (aren't medical euphemisms wonderful!) I have added short rows to the raglan back above the armholes. Incidentally, as this stitch compresses the work vertically I decrease the raglans every 4th row to the start of the shoulders and only then change to decreasing on alternate rows.
It's a pleasant stitch to work, not difficult, but with enough interest not to be boring. And as you can see (the cardigan shown above is the third I have knitted in this stitch) I love it!