Who should i cosplay?

Right well im gonna cosplay for my friends birthday and im not going to buy a costume just sorta make it up out of stuff you can get in the shops, i have longish really dark hair and brown eyes im 12 and just over 5ft im a bit fat but im gettin skinnier! Please help and im not gettin my hair cut or dyed or spendin loadsa money I cant be rukia because my mate said you have to be someone different from last time.