First and foremost: do not start with a song you learned from a cd in the past week. the song you start with must be one that is yours thorugh and through.

If the chorus is simple enough you can teach it to the audence and have them singing along. Don't expect them to do well the first time through. Know your audence, if they are all musical people they are likely to sing along. If your playing in a lounge to a bunch of businessmen they may not be willing to try. (open mikes general indicate the former, but there is variation amount musical gatherings and you should know them. Eaiser said then done)

Remember that a chorus isn't the the only way to do this. Some songs ahve repeated lines. Liam's brothers Poor Old Horse repeates the seconds and forth lines. You can teach these lines to a willing audence, and perhaps get them to pay more attention to how those lines fit with every verse despite the differnt action of each verse. Stan Rogers' Barret's privateers (in the database) is anouther good one that you can teach to the right audence.