Advice, recommendation, a good idea in the present.
Should/shouldn’t + V1
You should read more.
You shouldn’t play computer games so often.
Ought to + V1 (more stress on the moral obligation)
You ought to help him – he’s in need.
Regret about the past, someone didn’t do the right thing in the past.
Should + have + V3
You should have told me the truth.
She should have exercised more.
You shouldn’t have bought it. It’s too expensive!
For giving recommendation we can also use the construction had better + V1:
You’d better study more to enter this university.