Saying to someone "you'd better ___" is a very strong and direct way of telling them what to do. Here are some situations where you can use "you'd better ___":

• If you're a parent, you can use it when telling your children what to do.
• You use it when you're fighting with someone.
• You can use it in a friendly situation with friends, coworkers, and even strangers when telling them to do things that are easy, unimportant, and fun. For example:

  Hey, there's some free candy over in the lounge. You'd better go get some before it's all gone!

• As in the example at top, you can use it in a joking way to pretend that you're fighting with someone or treating them like your child.