Here’s an interesting way of increasing to start knitting cables, from Luise O’Neill of Impeccable Knits.
A tutorial for a crocheted cord called Spighetta Rumena. The text is Italian, but I think the photos are clear enough.
A crochet stitch pattern that is double thick for hot pads and the like.
Clothesline Crochet, which produces a stiffer fabric good for hats or baskets.