Some great advice in Cliff's post and I cannot stress it enough. People see you perform to one group they want to be next, especially if they're in some half boring conversation, and so you don't have time to be rummaging around in your pockets looking for props. Your entire wardrobe should be contrived to give you maximum storage, and you should know where everything is. You may want to be switching decks a lot, so make sure they're in a natural pocket.
As to approach, you'll notice that the first approach is the pain in the ass, but once that's overwith people around that group tend to notice you. I'm not sure what type of venue you'll be doing this in, but if you get a good reaction from one group, others tend to notice and you start clocking people lifting eyes in your direction. To be honest it is for this reason that I do wide spread panic by A. Fisher as an opener pretty much every time, if there's a suitable platform nearby, because its engaging, its a great opener, and you get great reactions, and a lot of laughter too if you plagerize his patter. -coughs-
As to an approach it depends, you have to watch very carefully for breaks in conversations, but whilst I've found it does help to let people know that you're there as a performer, it's even better to let them know you're also there as a person. Though just like in any situation what'll win people over is you approaching, shaking hands and intorducing yourself. Never lead with a deck of cards or a trick. Keep that in your pocket, or in one hand held at your side and give them a big smile, and say, "Hi, I'm dave."
If its a networking event of some kind people are doing that -constantly- anyway and so people expect it.
Dress like they do baring in mind that you have to have props invariably, but if I'm at a network event and some guy in a suit comes up and starts chatting nicely and becomes a part of my conversation then wants to show me a trick, I want to see it. Its not an interuption at that point.
Ask them how they are, get them engaged in you. Its easier said than done, but the best way is to treat it as a standard introduction, ask them some polite quesitons, they'll do the same, "how did you get here?" blah blah etc. Simple small talk stuff. Then a nice lead in, "Well...much as I'm enjoying this conversation I guess I better get to work." Then say nothing. Invariably one of them will ask (depending on the venue) about that statement, and you can say, "I'm the entertainment" or something cheesy and ask them if they want to see something. When you produce the cards/whatever you want to attract some attention. Don't be obnoxious loud, but be slightly louder. People in other gourps may seek eye contact when they notice you, make eye contact back with people in other groups at opportune moments, whilst maintaining focus on other groups. Once that's happened you have an immediate right of approach as other groups are already interested in speaking to you. It all builds up expectation, and as I said, nothing makes people want to see what you do more than hearing a group of people with you in it laughing and having fun, and remember, this isn't a David Blaine special. People are looking to be entertained, not horrendously baffled. The both can go hand in hand, but its better to be polite, well mannered and funny than it is to be weird magic and odd at most corporate events.
The single biggest thing I can say is, be natural when you approach. Don't approach as captain magic. Be a person, be nice, be polite, be likeable, don't wear the fact you're the entertainment like an albatros around your neck.
