The New Orleans Opera has been getting creative to appeal to new audiences. It's adopted the ideas of a New York group to present Opera on Tap, a gathering of opera fans in barrooms with previews of upcoming shows. Last Wednesday, the group toasted Puccini at the Rusty Nail (Formerly the Mermaid Lounge). The group is presenting Il Trittico, a trio of one-act operas (recast in New Orleans settings) by Puccini, next weekend (Nov. 16-18) at Tulane's McAlister Auditorium. As a special offer, the opera is offering first-time opera goers $20 tickets. Opera virgins need only call the opera ticket line (529-3000) to reserve a seat and get the special price. Any seat in the house is available at the special rate, so call early.