What should I do when joining MBA fair?

I agree with Ariel...definitely business formal (dress pants, nice button down shirt). I don't think a suit is necessary though. I definitely agree that you should not try to impress the people manning the booths, but really only ask questions you want answers to.

Thank you bb for moving my post here. And thank you Ariel and Miccarlo for sharing your opinions. You are right, there will be a crowd and I'm not going to impress the schools admissions. However, I think I know almost about the schools from their website, so do I really need to ask them questions that I know the answers?

I wouldn't ask questions I can easily find the answers to. Focus on items that are specific to your application (GMAT score, work experience, post-MBA goals, etc) basically try to gauge how they would view your application package. You can also discuss their placements in the area you're interested in. One question I've been asking admissions directors is how their career centers have handled the impact of the financial crisis on recruiting and the demise of all the bulge brackets. Some schools have better networks and are better able to fall back on smaller companies when times get rough than others. You want a school with a dynamic network and well-connected placement services. Do they have that?

I have not attended an MBA fair before (just school visits) so I am not sure if the actual adcoms come or if it is really just ambassadors to the school who can usually answer the general questions. I'm in the same boat with Ariel that you should try to focus on questions which are specific to your profile and goals as opposed to general questions about the school. Perhaps it would help to determine who from the schools are actually going to be there to represent.

You really gave me good ideas. I appreciate your opinions very much. I will think about more questions to ask them. One more thing, I'm off work at the moment, should I give them my name card?

I wouldn't. Most schools keep a list of people who stopped at their table and are interested in their program. You can put your name on that.

Many big schools now set up their own individual info sessions, rather than traveling in packs via MBA fair. (I think big schools tend to join the MBA fair for international purposes, but I could be wrong)

At these events, each school has at least one or two people from their admissions office. They will answer your questions (some schools have individual presentations as well) but all the answers to their questions will be really reserved in nature. They will give you standard replies. They will never say you will get in or not based on your individual stats that you provide them on the spot. Their goal is to get applicants interested in their program and encourage applicants to apply to their school. (ENCOURAGE is the key here)