I hunted through my yarn stash for some cotton, this navy cotton was perfect. I love cotton for accessories, it is firmer once the item is finished and with this sitting so close to my neck I find cotton wears better and is less likely to have me itching part way through a conversation.
And navy, well, it goes with everything!
You start the crochet collar with a chain which will form the top line of the collar. I used stitch markers (paperclips in my case) to mark every 10 stitches in the initial chain. I often get distracted during my crafting and have to quickly put my work down, I mark every 10 stitches so I'm not constantly counting and with 91 stitches in the initial chain counting would have been a bit of pain. I'm sure you can buy proper crochet stitch markers, paperclips work just as we'll and can generally be located loitering at the bottom of a draw!