Buy a visor made out of fabric that will absorb water, Sunwiser use Cotton or Cotton Lycra fabrics. This will help to reduce the amount of sweat running down your face while you play tennis.
If such a visor also has a thick headband, it will absorb even more moisture.
Check the weight of the visor. A lightweight visor will reduce the possibility of a headache, Sunwiser use lightweight Polypropylene. All the fabric Visors can be hand washed at 30% providing a clean, hygienic, smart and long lasting product.
http://www.sunwiser.co.uk/products_list.asp?catID=4&Name=PlaitedVisors
If the visor is too tight, it will leave sore spots around your head and cause a headache.
Sunwiser combat this problem by creating visors with plush headbands.
Select a tennis visor that you can easily wear, Sunwiser patented plaited visors have elastic, the Flexi visors with a soft “springlike” strap that automatically adjusts to any size.
Look for a visor with a neutral color underneath the bill. Neutral colors, like green, gray or black, help cut down on the glare from sunlight.