Convincing a person to do what you want can be a manipulative, but it doesn't have to be. You should not use it to entice a person to act in a way that will damage his well-being. Children are a perfect example of people who sometimes need convincing to do something that will benefit them. Sometimes you need to trick a little child into behaving in an appropriate or healthy manner. It is important to remember though, manipulation shouldn't be used to benefit only you.
Ask them nicely to do something. Rather than trying to manipulate them into action, say words and phrases like "Please" and "It would mean a lot to me."
Tell them that you'll time them and bet that they can't do it by a certain time. Though this is quite manipulative, children particularly will often jump at the chance to try to prove they can do the action quickly.
Pay them. Most economies are based on paying people to do things. The challenging part is deciding how much money it will take to convince the person.
Dare them to do it. This is an especially useful tool to convince someone to do something out of their comfort zone. For example, dare a friend to ask a girl out or dive into cold water.
Make a weak argument against a decision you want someone to make. This will get them thinking how wrong your stance is and they might be more convinced to do the opposite. For example, if you want your wife or husband to get milk from the store you might say, "No, we don't need milk. You just won't be able to eat your favorite cereal in the morning or have creamy mashed potatoes for dinner. And our child can do without his calcium for a day."