Dressing for interviews

The next time I go to the Vineland Swapmeet in La Puente, I'm going to buy a dark purple dress shirt and a tan pair of dockers. When I go to an interview I always wear a short sleeve shirt(just like the kind drew carrey or dilbert wear) among with some nice pants and black dress shoes. I think the shirt gives off the wrong first impression and with new clothes I can make a better impression. I call it my nerd look