How to stop other peoples from taking advantage of you?

So you're a good person and like to help others, but sometimes you feel that people are taking advantage of you. What will you do? Do you let them take advantage of you? No, stop it.

What you can do?

• Don't let people do things that you don't like.
  
• Get used to say No to things which you don't really like.
  
• Don't offer reasons & justifications for your decision.
  
• Your want's & needs are just as important as theirs, so tell them that.
  
• Consider the request. Decide if it is something you want to do and if you have the time to do it. If you are not sure, tell them you need time to think about it and will get back to them.
  
• Say "no" immediately to things you do not want to do or do not have time for. There's no need to put it off if you already know the answer. Be kind but assertive with your words and body language.
  
• Say something like, hmm, interesting. I'll think about that and come back to you. Or Thank you, that sounds like a great idea. Let me do some research into it, and I'll get back to you.
  

What do you think? Did I miss anything? Any better solutions?