Had better + bare infinitive

Had here is an unreal past; the meaning is present or future:

• I had/I'd better ring him at once/tomorrow. (This would be a good thing to do/the best thing to do.)

The negative is formed with not after better:

• You had better not miss the last bus. (It would be unwise to miss it, or I advise/warn you not to miss it.)

Had here is usually contracted after pronouns and in speech is sometimes so unstressed as to be almost inaudible. Had better is not normally used in the ordinary interrogative, but is sometimes used in the negative interrogative as an advice form:

• Hadn't you better tell her first? = Wouldn't it be a good thing to tell her first?

You had better is a very useful advice form:

• You had better go. (It would be best for you to go, or I advise

you to go.)

In indirect speech had better with the first or third person remains unchanged; had better with the second person can remain unchanged or be reported by advise + object + infinitive:

• Mike said, "I'd better hurry" = Mike said (that) he 'd better hurry.
• Mike said, "Ann had better hurry"  = Mike said (that) Ann had better hurry.
• Mike said, "You'd better hurry" = Mike said (that) I'd better hurry or Mike advised me to hurry.