What most naturally follows?

How to tell a friend you don't want to make plans with them
Remember, you have a right to say no.
Just because someone asks you to do something does not mean you are obligated to do it. If they want to do something with you but you don't want to do something with them, they shouldn't get their way over you; what you want matters, too.
Don't fall for a guilt-trip. Some friends can be pushy and will try to convince you to hang out even after you have said that you can't.