Make sure your slides are in focus. If your slides are not in focus, or the committee members have to try to hard to figure out what your artwork looks like, chances are you won't be selected. Use a tripod to keep your camera steady. Photographing three-dimensional work can be especially tricky. If you don't have enough depth of focus, some parts of your artwork can end up sharp while other parts are blurry.
Adequate lighting can help.
Make sure you use the right film to capture the true colors of your artwork. Different types of slide film emphasize different ranges of color. Check with a photographer to get advice if you are unsure which type of film is appropriate, or whether a particular kind of filter would help. Photograph your work on a neutral background, or mask your slides. Unusual backgrounds can be very distracting and detract from your work.