• We use should /shouldn`t + infinitve without to to give advice:

You should talk to you mum about it.

You should`t worry about what they say.

  • We use could + infinitive without to to make suggestions:

You could try taking up a new hobby.

You could make up with her.

  • We can use ought to / had better + infinitve without to to give strong advice:

You ought to do something about your son. He`s out of control.

You look terrible. You`d better stay at home today.