Focus on being conservatively dressed. This would exclude items such as halter or tank tops, miniskirts, shorts, spaghetti-strap or strapless dresses, and torn T-shirts or jeans.
Dress comfortably. You are likely to have a long day.
Wear layers. Temperature in the courtroom could be warmer or cooler than you prefer, so be prepared for either eventuality.
Be sure to bring your eyeglasses or other items you will need during the course of the day.
Consider the outside weather. You may have to park a considerable distance from the courthouse and will have to walk both ways.
Remember to bring your jury summons with you.