Making your own mermaid costume is great fun.

I didn't want to be Ariel the little mermaid but rather a more creepy looking nymph like the ones from the Peter Pan movie. (Photo)

So I decided to dye my hair red and put a lot wet gel in it. I also decided to wear colored contacts. My Make up was very light with a hint of blue on the eyelids.

I'd recommend to decide on a certain type of mermaid before you start.
These mermaid pictures and mermaid costumes can be a good inspiration.

For the outfit I chose a dark grey, sequined, skirt and added some tail shaped fabric at the back.  I attached the tail with a loop around my wrist when I was walking so no one would step on it.
The top was a lighter grey tank that I embellished with sequins for a scaly effect.
I used seaweed imitations in my hair and on my skirt and added stripes of fabric dangling from my mermaid costume. A also sewed on a dorsal fin.
The only jewelry I wore was a seashell charm.

I looked quite strange, like intended and got some great comments about my mermaid costume.