Interview soon.. any last tips?

i have a job interview in about 3 hours. Any last tips? Im trying to get a summer job as a litter picker upper. There are two other people trying to get my job. Should i wear a suit, tie and leather shoes? or just a T-shirt and jeans? should i wear my collar shirt with ons and colorful stripes? should i bring my resume, even though none of us did? she asked a few people if they wanted to be litter picker uppers. Three people, including me said yes, so now i have an interview... any tips?