As a contestant you want to always get the most out of your clothing. In order to prevent gaps, bra straps, or panty lines, you will want to consider using wardrobe tape. You can find effective ways to purchase and use wardrobe tape on this site:
Discount Surgical:
http://www.discountsurgical.com/details.asp?ProductID=13915&gclid=CM2bhcvC4qUCFSJ0gwodQVW-fg
Miss Oops:
http://missoops.com/miss-oops/mishap-tape
Hair Tape: