Prepare your hair. Because it looks like you will have cornrows-style hair over the next few weeks, you want to make sure to start with a clean, well-conditioned hair. Wash your hair with regular shampoo, and then use conditioner to soften it. Then you will also need hair oil for some parts as you braid, to make your hair soft, curly, and easy to set and shape.
Determine which parts later. Cornrows can be braided from any direction, so it is important to determine which parts before you start braiding. The two most common styles are to form a straight line following your hairline straight back to the nape of your neck, or braided in a circular shape around your head from the middle direction. You will need a densely toothed comb to divide your Hair into the pattern you want, and to separate your hair into a ready-to-braid strand.
Share your hair. Fill the spray bottle with water and a little olive oil, and shake it flat. Then, spray into strands of hair that you are working on. Use a comb to separate these hairs into lines down to the bottom of your head. The smaller the part, the smaller the braid; the bigger the part, the bigger the braid. Use a butterfly clip to hold the rest of your hair away from your face.