How can you stop your child begging for something you have said 'No' to?

From my personal experience with 3 kids, I like using encouragement with children and setting consistent limits and boundaries while you are at the store. Prepare them before you go in by saying something like, "Today we will not be buying any toys or treat" so they know what to expect. When we always buy something for them at the store, they will come to expect. Instead of rewarding them with something at the store for being good, just do it as a surprise at times so that the expectation is not there. Also, give your child a chance to earn money at home by doing extra chores so that they can come to understand and appreciate the value of things and allow them to save for and purchase what they choose and can afford.

Keep the times you say 'no' consistent. If they know that in the past you've changed your answer from 'no' to 'yes,' they will continue to beg. Also, try to avoid negotiating with them over it. Oftentimes, I see parents negotiating with their children after they start to beg. This re-enforces begging, as they know it'll result in negotiating the initial answer.

Usually I find it most helpful to get down on their level, look them in the eye, and tell them the answer is no and will not change, and if they ask again they will be put in time out/privilege taken away, etc. Then it just comes down to consistency. When they ask again, follow through with the discipline you told them would follow, and ignore their begging. When they see you will follow through, and that your no means no every time, they will learn it's not worth asking over and over.