We should leave. It's dangerous.

You should have gone.
(If you had gone last year, the situation would be better NOW.)

You should have gone.
(The above assumes that the "better" part was in the past: You didn't go last year, and LAST YEAR it would have better if you HAD gone.)

When you cough, it's best to cover your mouth.

Even when the lesson isn't interesting, you shouldn't yawn in school.

What direction should we go in now?

What do you think? Should we go or not?

This drink tastes horrible, so you'd better swallow it quickly.

You shouldn't abandon your original idea.
(Here the meaning is that your very first idea is better than the current one.)

You shouldn't abandon your original idea.
(The meaning here is that you came up with a new and unique idea that you shouldn't abandon.)

His decision that we should fight against the Omaticaya was a bad one).

You shouldn't go.

You should have gone.

You should go.

Tsenu: I believe it was a mistake for him to have gone.
Kamun: No, no! He should have gone!