better to drill smaller holes and increase the size or just go for it
on the first try? *

I like to use exact size holes I want the first time. I thought it was
safer (reduced exposure...), as well as faster, but, Tim has a great
do's and don'ts for this very thing (again, on W&W, Thanks Tim!...)
http://www.wingsandwheels.com/Installation.htm and he recommends step
drilling... Lots of really good tips there (including carefully and
lightly chamfering the edges of the holes w/a countersink bit)

-Paul