Advice: Should, Ought to, Had better

Modal verbs are used to express modality. To express advisability, should, ought to, and had better are used.

Form: Subject + should / ought to / had better + verb (bare infinitive)

Should and ought to have the same meaning. They are used to give advice, or say what is the right thing to do; for examples,

• You should /ought to call your friend to thank her.
• You shouldn't/oughtn't to tell lies.

Had better (or 'd better) has also the same meaning, but it's stronger. It implies a warning or threat of possible bad consequences; for examples,

• It's raining; you'd better take your umbrella.
• I have a very important meeting at 8; I had better not be late!