I would more or less repeat the advice that you've already seen posted by others. As the choices are being read, have your fingers ready over the buttons. I tend to use my thumbs. The lights will light up about the time that the host reads the C choice. By that time, you should have a pretty good idea of the correct answer. If you know it is A, start clicking A repeatedly as quickly as you can. The same is true for B and C. If you know it is not A, B, or C, then start clicking D even though you may not know what the D choice is yet. One word of caution though, if you cannot completely rule out A, B, and C, WAIT until you see the D choice before clicking on it. I've seen it happen too many times where someone had decided it wasn't the A, B, or C choice but then saw the D choice and realized it had to be A, B, or C. Here's a perfect example of this:
Awhile back I attended a show where a question came up asking you to identify which of four characters was not known as a James Bond villain. The choices came up as
A. Dr. No
B. Goldfinger
Of course, even people with very limited knowledge of James Bond films generally would recognize both of these characters by name, especially since the movies they were featured in share their names.
C. Rosa Klebb
Based on the process I decribed above, at this time you would either be clicking C or D. Well, I think many people in the audience didn't recognize the name of Rosa Klebb so they chose C. I know this because when
D. Dr. Evil
was revealed as the last choice, you could hear an audible groan from the audience. Clearly many people chose C and then immediately realized their mistake when Austin Powers' nemesis was the D answer.
For those that don't know Rosa Klebb by name, she was the villain in From Russia With Love that had the shoe with a knife protruding from the front.
One other suggestion, once you start pressing the buttons, do not stop until one and only one light is lit. I have let off the buttons prematurely before and realized it when I looked down and all four lights were lit. It is an easy mistake to make.
Rob