'Tom-Boys' can be weeaboos too my darling Maid-To-Be.
Really what we're all trying to get at is you don't have to act like Paris Hilton to be an interesting person. Let's just be completely honest here, the people going to Maid Cafe's are there to see YOU the maid. Unless your cafe is serving something unique (IE:Authentic cuisine) the people coming in are there to be charmed by cute girls in maid outfits. No beating around the bush here, they want to see attractive ladies with nice personalities serving them tea in cute little loli-maid outfits.
Be welcoming, authentic, and personable. Unless the cafe you're working at prefers a formal atmosphere (which is rare at conventions) you don't need to treat guests like they're patrons at a 5 star New York restaurant. Be relaxed and just nice.
Remember to keep in mind, you supply your own outfit. Very few maid cafe's have specific uniforms (I think I only saw one a few years back) so you will want a high quality outfit to wear. A cheap frayed lace Halloween bagged costume does not a Lolita make.