We should think of the consequences before we act

 I'm pretty sure you know what you are doing, but it always pays to look before you leap

Sono sicuro che sai quello che stai facendo, ma non fa mai male pensarci bene e non buttarsi alla cieca

Are you going to quit your job to move who knows where? Look before you leap! You know nothing about your future job, your future house and you don't even know where you want to go!

Vuoi licenziarti per trasferirti chissà dove? Pensaci bene! Non sai se avrai un lavoro decente, una casa decente e poi non sai nemmeno dove vorresti trasferirti!

This expression could be based on Aesop's fable "The Fox and the Goat" written in the 500s B.C. The story goes that a fox falls into a well and cannot get out. A thirsty goat happens by and the fox talks him into leaping into the well to get a drink. The goat jumps in and the fox climbs upon the goat's back and horns to get out of the well. When the goat asks the fox for help to get out himself, the fox replies that the goat has only himself to blame, because he should have looked before he leaped.