Selling your wire-work jewellery at a fair requires a number of skills. You will need a very good display, as wire-work is relatively small and shapeless. Putting your pieces on a bust giving them a shape and height is a good idea.
Keep your eyes open as jewellery is small and relatively easy to steal. Keep a list of what you started with, what you sold and do a stock check at the end. Any losses will have a big impact on your profitability.
Take a look in your local jewellery stores to see how they are presenting things. You can use trees and other table top displays.