When starting to knit, Garter Stitch is arguably the easiest of all stitches to knit.
Indeed, that's all you do, one stitch, the knit stitch - on both sides of your knitted work.
Every row, knit.
Garter Stitch won't curl at the edges like stocking stitch can.
Multiples of stitches are not required, however, you will find that compared to a tension square in Stocking Stitch there will be more rows present in Garter Stitch to a 10cm (4in) square, thereby using more yarn than stocking stitch.
when knit flat
Knitting needles: 4mm / USA 6
Tension of yarn if knit in stocking stitch: 22 stitches and 28 rows = 10cm / 4in square
Cast on required number of stitches.
Every row k.
Cast off using a knit stitch.
Read each row right to left.