Make sure you comfortable and feel confident in what you are wearing. Choose an outfit that is appropriate to your audience.
Avoid anything too tight.
A looser fit is more flattering.
A paunch on a man is best hidden by buttoning a good fitting jacket.
Women should avoid low cut blouses.
It’s worth checking what colour the stage set is and if possible compliment or contrast with it.
Make sure the colour you wear compliments your skin tone, hair and eye colour and does not over power you.
If you are small a brighter colour may help you to stand out.