newinmay offers great advice.
I was amazed at what wearing a tie does for me - I feel better about myself and seem to have a bit more credibiility (all about perception I guess).
Another excellent point is having the blue-collar experience, especially if you're working your way through school. That seems to draw alot of respect from your peers and potential employers.
I found the people pretty much the same only they had more money. The most awkward moments come when they talk about the things they are able to do with their money. Flying back and forth to McMansions every couple of months is still foreign to me. Some once asked what kind of exotic tile I had on my shower, I replied: Well, in the shower I rent, it's one big plastic tile that hangs from a rod.
I think it ends up being evident who is where in the economic spectrum and the conversations morph accordingly. When I walk into a meeting of high-rollers, the conversation adjusts to a level that is to comfortable to everyone and I appreciate that. And I believe that they know I appreciate it and are happy to do it. It also allows them to 'de-suit' and talk about their early careers or their blue-collar jobs. Funny how many of us have had the same blue collar experiences - it's a unifying, paid your dues, kind of thing.
But yes, observe, and then slide in. Actually, people in the cubicle still cuss, chew tobacco, smoke, cough without covering their mouths, don't wash their hands after 'going', have coffee or breakfast dripping down their shirts or something hanging out of their nose. You'll see.
I sincerely hope that helps.