You use should/shouldn't to give advice.
1 A: I want to be an actor. Should I leave (leave) school now and go to Hollywood?
B: No, you shouldn't yet. You should (go) to theatre school after you finish school.
2 A: I love working with animals. My parents want me to get an office job. What should I do?
B: Well, you shouldn't (work) in an office! You should (train) to become a vet.
3 A: I'm scared of heights. Should I go (go) walking with the class this weekend?
B: Yes, you should, but you shouldn't (tell) the leader and you shouldn't (climb) any mountains.