I usually dont open with effects, but rather by formally introducing myself.
me: ''Hi guys, I'm Daniel, your complimentairy magician tonight.''
Audiance: ''reaction X''
me: Hey you guys want to experience the impossible? (I dont say: ''something cool'' or be baffled, it sounds lame
Me: Great, well first I'm just wondering if this is yours? (knife with dollar strapped to it). Do a trick by Jay Sankey called money making machine, using the paddle move. (any kind of trick really).
In my experience the key is letting the people know your
B) Proffesional/The Magician
C) Come in at the right energy level (little NLP I use here)
D) Not going to waste their time/be gone in a jiffy (I use time constraint techniques here, also NLP)
I often tell the audiance A.
B is a little harder, its your character/congruence. I usually walk in wearing a suite/something classy. And I wear a Fedora with an Ace of spades in the band around it (The game: Godfather II gave me the idea). The rest is just how you act.
C: Energy levels is slightly more difficult, all I can say is try to come in at a slightly higher energy level. (You controll your energy level by way of speech/body movement.) If a group is very loud/having fun come in at a loud tone and have large arm movements! Make sure you're flashy and fast. If you come in with a to low energy level the group will sense you're going to dull the mood and most likely reject you.
D) Time constraint is done by saying: Can I show you something real quick. Or by doing a technique called body rocking.
Body rocking: Move in at a slight angle and give all physical signals that you're going to be walking away after your first sentence. Once their listenting turn your body so you're facing them. And continue as normal.
Hope this helps,