In terms of magic, I typically produce some sort of giveaway for the spectators. When I was the featured entertainment in high-end restaurants or resorts, I was a fan of making a bottle of champagne appear from under a silk to introduce myself. My business card would be conveniently pinned into the cork of the bottle. In terms of street magic, I would make a pack of matches or pack of gum appear from a sudden flash of fire to naturally lead into a following effect. It would give me a perfect opportunity to perform Dan White and Dan Hauss' Lit or Richard Sanders' Trident Sugarless Bill.
I've been making the move into more serious mentalism in recent years, and I find that my favorite opener right now is System 88 by Docc Hilford. I'm a major fan of it. After asking a spectator five questions, you proceed to tell her very specific and intimate details about her personal life. It's a very emotional, interactive effect and is structured perfectly for an opening sequence. It looks and feels like cold-reading, but it doesn't require any such skill. Rumor has it that PUAs used similar ploys to attract women and after experimenting with this effect, I can definitely understand how it would work.
How many warm-up effects should you do before the meat of your routine? One is all you should need. Seriously, especially if you plan on working professionally and doing magic for a living. One 'warm-up' is all you could afford. That's why an opening effect needs to be loud and captivating. It needs to be interactive and demonstrate who you are and what you do. Once you put that out on the table, the audience should be able to make their decision as to whether or not you're worth their time, and that will illustrate exactly what kind of quality performer you are. That's the truth. You really shouldn't compare yourself to what you see on television, because the methods employed on TV and the ways in which telemagicians acquire those kinds of reactions are often unrealistic in the real world working environment.
RS.