Had Better

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.
EX:You'd better tell her everything.
The negative form is “had better not”.
EX:
You'd better not say anything.
We use “had better” to give advice about specific situations, not general ones. If you want to talk about general situations, you must use “should”.
EX:
You should brush your teeth before you go to bed.
When we give advice about specific situations, it is also possible to use “should”.
EX:You shouldn't say anything.
However, when we use “had better” there is a suggestion that if the advice is not followed, that something bad will happen.
EX:
You'd better do what I say or else you will get into trouble.
THAT is to say,
"Had better" is most commonly used to make recommendations. It can also be used to express desperate hope as well as warn people.

Examples:

You had better take your umbrella with you today. recommendation
That bus had better get here soon! desperate hope
You had better watch the way you talk to me in the future! warning

Using "Had Better" in Present, Past, and Future

Most modal verbs behave quite irregularly in the past and the future. Study the chart below to learn how "had better" behaves in different contexts.

Use	Positive Forms 1. = Present 2. = Past 3. = Future	Negative Forms 1. = Present 2. = Past 3. = Future	You can also use:
had better recommendation	1. SHIFT TO "SHOULD" OR "OUGHT TO" People should unplug toasters before they clean them. 2. SHIFT TO "SHOULD HAVE" OR "OUGHT TO HAVE" You should have unplugged the toaster before you tried to clean it. 3. You had better unplug the toaster before you try to clean it.	1. SHIFT TO "SHOULD" OR "OUGHT TO" People shouldn't clean toasters without unplugging them first. 2. SHIFT TO "SHOULD HAVE" OR "OUGHT TO HAVE" You shouldn't have cleaned the toaster without unplugging it first. 3. You had better not clean the toaster until you unplug it.	should, ought to
had better desperate hope, warning	The movie had better end soon. They had better be here before we start dinner. Desperate hopes and warnings usually refer to the near future.	They had better not be late. They had better not forget Tom's birthday gift. Desperate hopes and warnings usually refer to the near future.