Here is a review of different stitch lengths. In our hat we did double crochet, but it’s good to memorize the main stitches. Note that the instruction for all of these is for crocheting a rectangle as opposed to a circle, and so set up instructions will differ.
Here’s a review of Single Crochet. This is a dense, fairly stiff fabric which I use for potholders and washcloths.
Here’s a review of Half Double Crochet. This creates a slightly more flexible, very versatile fabric.
Here’s a review of Double Crochet. This is the longest, drapiest stitch that is commonly used, and is called for in our hat pattern.
Here’s a review of Crochet Slip Stitch. This is different than a knitted slip stitch.
Here are some cool tips for changing colors and weaving in ends as you crochet to reduce the amount of ends you will have to weave in later. I like crochet over my end, skip a spot and do a hair-pin turn, pushing the yarn back into the work to help lock it in place. This is especially important with granny squares and small motifs.