Meaning:
think carefully before you do anything which uncertain

Synonyms:
Look twice before you leap.

Sentences：
It is important to look before you leap.
I’m not saying you shouldn’t sign the lease for that apartment. I’m just saying you should look before you leap.

Conversation 1
A: I’m thinking about going to night school.
B: Are you sure you can spare the time and the money? Look before you leap

Conversation 2
A: Did you read today’s paper? Stock prices rocketed. 
B: Yes, I did. So I will invest all of my money in stocks. 
A: Cool down. Look before you leap. 

Conversation 3 
A: What is the matter with you, why are you crying?
B: I have made the most stupid mistake.
A: Calm down, what have you done?
B: I quit my job because my new boyfriend told me I could get a job working with him.
A: So what is the problem?
B: He left me last night, he was lying.
A: Oh dear, you should have looked before you leap.

Conversation 4
A: I’m going to go to Queensland next week.
B: Great, what are you going to do there?
A: I don’t know, I’ll get a job and find somewhere to live.
B: Have you got any offers?
A: No, nothing. Everything will be fine.
B: Maybe you should look before you leap

（Callan book stage 8, 735p）