In an office or studio setting, a suit would be appropriate. Wear clothing to which a tie-clip microphone can easily be attached. This means a tie or clothing with lapels. You'll also want to avoid wearing scarves or items that hang down and cover the microphone. Another aspect of your appearance is your body language and movement.
Many people get nervous when the camera is turned in their direction.
Knowing what's in store can help diffuse some of the nervousness, and there are ways to appear calm on TV even when you are nervous. Avoid large and quick movements. Slow, deliberate gesture are best, especially when demonstrating a technique or practice. Slow movements are much easier for the viewer and camera operator to follow. More times than not, you'll be interviewed by someone.