Like every destination, Las Vegas has its own rules one must follow in order to have a good time. Some rules are laws, and some are just part of the culture of Vegas. It is a good idea when traveling or living in, a location, to know these rules.
One of the most common misconceptions about Las Vegas is over prostitution. No, it is not legal in Las Vegas. Despite what the hand bills that are handed out to you on the Strip imply, prostitution is illegal in Clark County. Other counties in Nevada however allow some form or another of legal prostitution in sanctioned locations. Nye county being the closest to Clark County, is home to some of the more reputable places if your curiosity is seeking that sort of thing. But make no mistake, you cannot engage or solicit any of these services in Las Vegas.
As of January 2012, it is illegal to talk or text on a hand held device while driving. Yes the police can see you, and if they do you can be fined up to $250. Las Vegas has seen a rash of traffic accidents recently so it is a touchy subject you will have a hard time talking, or texting, your way out of. This is taken very seriously in Las Vegas, so just don't do it.
Less serious and less dangerous, another place you can not use a cell phone is in a casino sports book. For obvious reasons of not wanting betting patrons to be in contact with pre winners information, you will have to make all of your calls, texts and internet searches outside of the sports book.
Other rules may not land you in jail if you break them, but it will get you bad service or "the look" from the casino employees. Tipping is big business in Las Vegas. While it is fairly standard in US cities to know that you tip the bartender, the cab drive, and the food server, it may not be so common knowledge who to tip in a casino. The short answer is, if you are a winner, everyone. To simplify, make sure that the service people who tend to your winnings, whether it is at a casino cage, or the dealer who dealt you the winning hand, get a tip. Ten to twenty percent to the most immediate person who provides you with the money and a little less to any other service person who helps handle the transaction. You can also play a hand for the dealer and let them enjoy your winning streek as a tip too. Extra special service from any of the other employees, winning or not, should be recognized with a tip as well, computable to the service they provide you.
Every region, county, state and city has its own set of rules, both legal and social you should know before traveling. Las Vegas is very easy going, anything goes type of city, but even Vegas has a few things you should know before visiting.