*I've been to the Vegas convention every year since 2002, plus other Star Trek and general Sci-Fi conventions in Vancouver BC, Seattle, Portland, Los Angeles, and Salt Lake City (I think around*50 or so in total since my first one in 1992). Here are my suggestions--
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* Talk to people in line around you. I have met people from all over the US and from all parts of the world, including Japan, England, Scotland, Germany, Australia, Chile, Canada, Spain, Peru... A big part of the fun of the convention for me is just talking with other fans, and I see many of them again each year. If you have business cards, or just make some up on your home computer, it makes it easy to trade email addresses or Facebook information.
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* Bring some snacks. There is food available in the hotel in a number of restaurants and quick service areas, but if you throw a few granola bars, fruit, beef jerky, *or whatever you like to munch on into a backpack, you can save money for things from the dealer's room*In the past, the previous*hotel had*provided large jugs of ice water and plastic cups in the actual convention hall, in the dealer's room, and outside the convention hall, so you don't have to worry about bringing bottled water unless you really want to.
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* Bring extra batteries and memory cards (or film) for your camera. Besides getting shots of the stars while they are on stage, you'll see a lot of folks in some cool costumes. Most of them don't mind at all if you take a photo with them.
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* Dress up if you can-- it just adds to the experience. I'd say that at the Las Vegas convention, about 20% of the attendees wear a costume of some sort, or at least a uniform top with jeans. About another 20% wear a Star Trek t-shirt or baseball cap with regular casual clothes, and then the rest are mostly in shorts, jeans, and T-shirts. I like to bring a different costume for every day and really go all out. In the past, I've dressed like a Klingon, an Andorian, Captain Kirk, *Mr. Data, Lore,*and a Borg. This year, I'll have some new costumes including Data as Sherlock Holmes, Data transformed 1/3 human by the Borg Queen, and KIROK.
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* Despite being in Las Vegas in August, the actual convention hall tends to be on the chilly side because of the air conditioning. If you get cold easily, you might want to bring a sweater or a long-sleeve shirt.
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* The Dealer's Room is large and has a nice variety of things, from actual screen-used costumes and props (these can get pricey) to models, toys, patches, fan-made uniforms, action figures, videos, books, art, t-shirts, 8X10 photos, posters, CDs, etc., and not all from just Star Trek. There is merchandise from Star Wars, the X-Files, Battlestar Galactica, etc. Most of the vendors are equiped to take credit cards, but having cash on hand doesn't hurt.
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* I am not really into autographs or photo ops, but the lines for really popular stars can be REALLY long (sometimes over an hour). Photo ops and autoraphs can sell out quickly, so if there is someone you would really like to get, buy your ticket for them sooner rather than later.
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* There are other supporting actors in the dealer's room, and generally you just walk up to their table if you would like a photo or an autograph. The Creation website has the price list for each person appearing.
Still keeping an eye out for the desert robe 
