If you're a fan of Pokemon, you can create a gijinka.
Which means a "human" version of a certain pokemon. You have brown hair and eyes, you can pull of a brown outfit and be an Eevee so to speak. You can be as creative as you want. You can also add ears and a tail.
You can look it up and see any ideas! :) Enjoy and have fun!
How long is your brown hair though? Lol the easiest characters I can imagine to cosplay would be characters like in K-ON and similar shows. You don't necessarily need the uniform and can wear clothes from the EDs or clothes they appear in outside of school in the show. You can get a black wig and easily be Mio with a purple hoodie, white short sleeve button down shirt, blue plaid skirt, and black knee tights. Ritsu wore a simple black hoodie, white shirt, yellow track shorts, and blue spandex tights in the No, Thank You ED. In the new Singing! ED from the movie one of Mio's outfits is just a pink dress and Mary-Jane shoes. The other outfits were a bit more complex though but if you get two yellow hair things like Yui and a black hoodie with bear-like ears I'm sure people would figure it out without the rest of the clothing. (If they've seen the movie).
The brown eyes don't really make too much of a difference since people cosplay characters without having the matching eye color anyways. Hair dye isn't too expensive but make sure someone who knows what they're doing is putting it in or be very careful. Wigs are fine too.
Here's Yui in the outfit I was talking about. Lol her shoes are converse!