I use a 3mm hook and Cleckheaton Natural cotton 4 ply. You can really use anything you like, I just find cotton feels best. Bamboo and Soya are also great options. I avoid wool only because it takes so long to dry out.
I use these once, let them dry out and once a week I throw them into the wash with any regular load of washing -I do put them in a little draw-string bag so they don't get lost in the wash. You can of course hand wash them. I'd use pretty hot water if hand washing though, to make sure any oils or residues are well removed. I find these are best for washing your face, pop a little face wash on the wipe, it lathers up really well and each of the little crochet stitches helps to exfoliate. For applying toner, I use reusable cloth wipes, which I will post a tutorial for at a later date.
Unless you plan on washing these more often than once a week, I recommend you make enough to last you. I am up to 11 wipes and so far only perhaps 1/3 of the way through a 50g ball? So they're very economical to make.
Create a Magic Loop. (For instructions on how to do this, see here.)
12 double crochet into magic Loop.
Pull tight and slip stitch to create a circle.
Row 1: Chain 2 (counts as first double crochet) 2 double crochet into 11 remaining stitches
Row 2: Chain 2 (counts as first double crochet) 2 double crochet into 11 remaining stitches
Row 2: Single crochet into each stitch.
Bind off and weave in loose ends..