USAGE:
"Had better" is commonly used to make recommendations. It can also be used to express desperate hope as well as warn people.
Examples:
recommendation.............You had better take your umbrella with you today.
hope.......................That bus had better get here soon! (I hope the bus gets here soon)
desperate warning..........You had better watch the way you talk to me in the future!
"Had better" is often simply pronounced as "better" in spoken English.
Spoken English: They (had) better be here before we start dinner.
FORM:
We use “had better” plus the infinitive without “to” to give advice.
Although “had” is the past form of “have”, we use “had better” to give advice about the present or future.
Examples:
You'd better tell her everything.
I'd better get back to work.
The negative form is “had better not”.
Examples:
You'd better not say anything.
We'd better not miss the start of his presentation.