Any two-colour cast-on will do. Slip the first stitch knit-wise, then alternate knit then purl stitches as when working a (k1,p1) rib, but work all the knit stitches with one colour and all the ...
Basic rib stitches like 1×1 and 2×2 simply alternate knit and purl stitches. Standard ribbing is easy to do and they look great too – offering both texture and stretch.
This helps create tighter purl stitches that match the size of your knit stitches. Experiment with Different Purl Methods: ...