[TapWaterBandit]

To add to this:

- Look before you leap. - Measure twice, cut once. - Stay silent and have people think you're a fool, open your mouth and confirm it.

I'm sure there are many more common idioms pointing towards the idea of "think before you act".

[jyriand]

Where I'm from we have similar sayings:

- Don't dive head first into water.

- Measure nine times, cut once.

And a random saying I just remembered: "Autumn has the eyes of a summer and the teeth of a wolf."

Edit:formatting

[shadowfox]

Err. What does that last one mean?

[tomasdore]

Maybe that:

- being late (acting in "autumn") ...looks/feels similar to

- being on time (seizing the moment at the right point, in "summer")

...but has a nasty bite?