Sorry, I haven't completely read all the other posts, so forgive me if I repeat anything.
I actually quite like KarenC's suggestion... it's different.
I've done bridal expo's and had 1/4 page ads in the local bridal magazine. I'm unsure of what the coverage is on the magazine, but certainly would've reached a lot more brides than the expo I was at. I received more queries and follow ups from the expo.
It's personalised, speaking with people, chatting about what you do... you're not there to sell. you're there to provide information/answer questions etc.
It helps to have a sample pack/bag or similar to hand to people as they pass, a a discount voucher for referrals etc. You've got to make it catchy because they'll be getting samples from everyone and you want yours to stand out. Find out if there are other exhibitors who do what you do. Research them so you know what you're competing against.... how can you get the upper edge on that market where there is competition.
By giving out a postcard discount voucher, or sample bag you'll reach more people, rather than just the ones who come to your stand specifically to find out more. Some will rush past but still take a bag. And who doesn't want a discount ...
certainly no hard sell need, just be friendly and approachable and have the info at hand so they can look at it later. They are more likely to remember you and like you for being human rather than a hungry sales rep.
It can be a lot of fun socialising and networking. I know I've had other businesses approach me for information as well as the people visiting the expo.
Also, if you have something special that no one else has, you may find that these people will go and tell others, which may bring more people back to you either on the day, or later down the track.
I definitely vouch for the expo over magazine advertising.
Put yourself in the customers shoes.... what are you more likely to look at, feel comfortable with, follow up on.
I got a lot of customers in to my stand by having a lucky dip (different valued vouchers). You could have a questionaire to get peoples details, win a prize and follow up on them later.
There's so much you can do at an expo which is only limited to your imagination.