Drilling holes through plexiglass.

Tomorrow is my birhtday so I am going to explain something simple that I did not know how to do until of course I did it the wrong way the first time. I was making a placard for a rare baseball card and wanted to put a plexiglass face over it with wood in the back. Needed 4 holes drilled in each corner to mount to placard, just drill holes right!! NO. I tried the obvious of course and when bit gets through it would shatter. Then went with the drilling in reverse trick and that was okay. But if you drill in reverse and also C-clamp a backer board on the exit side it will look professional.
JROD