There's nothing worse than a pitcher who can't see the catcher's signs. A pleasant 2.5 hour game can easily turn into an ugly 3 hour marathon when the battery can't get their communications straight.
Getting crossed up sucks, and trying to catch when you're unsure whether the pitcher is actually going to throw the fastball you signaled for or some other pitch is no fun either.
Seeing is Believing
The fact is, pitchers don't see very well (or else they'd be hitters, right?) I'm kidding...kind of. In all seriousness, sometimes shadows created by a catcher's knees makes it very difficult to see.
One solution would be to open up the sign stance or give the signals higher or lower. However, doing so might give the opposition a chance to peek in and introduces a whole new set of problems.
Paint it White
I've found the best idea is to keep a bottle of White-Out handy. Paint the back of your signal hand fingers making them easier to see.
This works better than tape because it won't interfere with your throwing feel. In a pinch, if you don't have the Wite-Out, moisten the back of your hand and drag it along the white chalk of the base line to illuminate the fingers.
Brent Mayne is a 15-year veteran of the Major Leagues. He ranks 75th in the history of baseball with 1,143 pro games caught, and his .993 career fielding percentage is 4th all-time. Brent is the author of the book "The Art of Catching"--a comprehensive guide to teaching and building defensive catching skills.