First, know that looking hot comes from being confident! Boost your confidence by making sure your uniform fits you well, standing up straight, and smiling often. You can also check...
If you can glitch the game into Director Mode (research on YouTube), you can buy anything in the game for which you have enough money - without losing any money.
Use the dullness to your advantage to bring out a brighter but smaller part of your outfit that will claim more attention. Perhaps wear eye-catching earrings, carry a small, bright...