Talk about the person using the item you are offering at some point in the future.

Mention how good she will look on her date wearing the jewelry you made, how happy his wife will be with the beautiful box, or how tasty the pie will be after dinner that night.

This gets the person thinking about the item as already belonging to them and how they are going to enjoy it and may heighten their emotional attachment to it making them more willing to make a favorable decision during the bartering process.