How can i get natural looking waves in my hair?

I have a shoulder length a-line haircut. My hair has been falling out a bit more than normal lately, so i've been trying to cut down on the blow drying and straightening. But when I let it air dry, it turns into a birds nest, regardless of how much product i put in it. My hair is too short to braid, and when i use a curling iron, it looks even shorter, which i don't like. I do have a diffuser for my blow dryer, but it really just makes my hair more frizzy. I've also tried drying it with my head upside-down while scrunching, and it does nothing. Is there an easy method i could try or product i can purchase to get natural looking waves/loose curls?How can i get natural looking waves in my hair?
you should use hair mousse. and then scrunch your hair. or just let it air dry.