1. Divide your hair into two equal sections.
2-4. Braid each section, and tie the end with an elastic band. You’ll want to do what’s called a “Dutch braid.” For a normal braid, you take the outside section and cross it IN FRONT of the middle section. A Dutch braid is the opposite: the outside section goes BEHIND the middle section. It’s important to do the braids this way so that they’ll look seamless when when you connect the two sections later.
5-6. Fatten out the two braids by pulling apart the outer edges. I like to “smush” the braid back and forth in my fingers, too—whatever makes them fuller and fatter and not so sleek.
7. Line up the two separate braids so they begin to look like one big fat braid. It’s important to make sure the middle section of the mermaid tail lines up–don’t worry if the ends of your braids (the hair that is sticking out underneath the elastic) are uneven, it won’t matter. It’s more important to line up the braid correctly, so the center of the tail matches.
8. Pin the center of the two braided sections together. I tend to use mini bobby pins since they are easier to hide, and I like to pin them in and up (you start with the pin facing horizontally, then as you push it into the hair, you direct it vertically). Use as many bobby pins as it takes, until you feel the braid is secure. I used about five little pins, and pinned about 1 1/2 inches apart, wherever I could best hide them.
(Optional step: You can remove the two separate rubber bands at the end, and just use one to combine the two tails together. I didn’t do this because I used smaller rubber bands to begin with.)