Match your trunks to your costume

If you perform a lot, you're probably familiar with dance trunks or briefs.  (If not, they're the high-waisted, full coverage underwear many female dancers wear under skirts to avoid flashing the audience.)
It's often easiest to match the color of your trunks to the color of your tights to create a seamless line (pink trunks go with pink tights, nude with nude, etc.)  This works really well with pale costumes like white romantic tutus.

However, if you have a colorful costume, neutral trunks can actually make you look more naked.  If the audience gets a glimpse up your red skirt and sees nude trunks, they may wonder if you're really covered.  In cases like this, it's best to find trunks that match the color of your costume.  Most brands produce dance briefs in red, blue, and black, and, time and resources permitting, a white pair can always be dyed to match a unique costume.

Matching your trunks to your costume isn't a necessity if time or funds are tight, but finding a pair the same color as your skirt is a sure-fire way to make your costume look spiffy and well-done from the audience's view.