Here's an idiom about caution. It's always a good idea to think carefully before doing something, particularly if there is some risk involved.
A leap is is a large jump; a bit like frogs do. In fact, there's even a game called Leapfrog when you jump over someone. You can also use leapfrog as a verb.
Kubica leapfrogged from third to first position in the race - well , we can dream!
Back to looking before you leap, here's an example where it's probably better not to look. Oh Matku!