Katniss Everdeen in The Hunger Games

For those that want to dress as Katniss for Halloween, cosplay oder for a costume party...

Lets start with the book:

Katniss wears a a light green bluse with her mockingjay pin, tawny pants, brown gürtel and a thin hooded black jacke that falls to the thighs. Her hair is done in a braid down the back. She also wears combat boots.

If Du want to go totally accurate Du can mess yourself up a bit, a wound just above the eyebrow and flame-painted fingernails (For those that have read the book will know).
And since Katniss has black hair and grey eyes, if Du don't have the colour Du can dye your hair...