As a part-timer, you may be allowed to come to work in casual dress. Try dressing professionally instead. Make it easy for your boss and co-workers to envision you as a permanent part of the staff. Dressing professionally will help you to earn the respect of those able to hire and promote you. Don't put on your track shoes at one minute to five.
Professionals are more interested in completing quality work than in watching the clock.
Think about the impression your are creating and focus on the work, not the time. Learn everything you can about the organization. Demonstrate your desire to move up in the organization by taking time to become familiar with the company's goals, mission, and structure. Take an interest in the company's activities even if they are not directly related to your current job. Don't make an issue out of things you don't like to do.