Look your best on portrait day
Your images will look best when the viewer's attention is drawn to your face.
It is best to dress in something very simple. If you are being photographed against a medium or dark background; darker, richer colors such as tones of burgundy, blue, grey, or brown are great.
For the ladies, a simple neckline on a sweater or blouse works well. Revealing necklines are not suggested for school portraits.
For the gentlemen, a plain collared shirt or sweater is great.
For both, long sleeves keeps the focus to the face.
Bare shoulders or tank tops generally make the subject look heavier. Stripes, plaids and bold prints take the focus from your face to the clothes.
This goes double for graphic tee-shirts and sweatshirts.
Be sure your clothes fit well. If it feels tight, it will look too small and you will appear heavier in the photograph.
Finally, practice good posture and HAVE FUN - BE YOURSELF. It will show in your portrait!