How we change what others think, feel, believe and do
Tell the other person something that will impress them and get what you want, even though it is not true.
Act confidently. Do not hesitate or otherwise indicate that you are lying.
When selling, say that you have already had a good offer, or that someone else is arriving soon.
When buying, say that you know you can get the item much cheaper elsewhere (and ask them to match the price).
When asking someone to do something, say that you can easily get another person to do it.
Take small truths and exaggerate them. Talk of dire consequences should you not get what you want.
And so on.
Well, I like this place but I've just had an offer of a similar house at a much lower price.
Yes, Dad, I've done my school work. Can I go out now?
If I don't get the day off work I'll lose my apartment and have nowhere to live!
Bluffs work when the other person believes what is said and feels that they must act or concede in order to achieve goals.
Bluffing is of course a dangerous game, as the other person may call your bluff. If you are found out, then you will be suspected for a long time into the future and will hence most likely fail in attempted other negotiations.