Find the good games. The VP games with the best paytables are findable, but they're rare. Naturally the casinos prefer that you play the stingier machines. In general, the Strip casinos have the worst machines, and everywhere else it's better -- off-strip, downtown, and locals casinos. But while good machines are rare on the Strip, some do exist. VPFree2 can help you find the good-paying machines.
Despite the importance of finding the best machines, most players don't. That's why casinos can offer both decent and lousy machines in the same casino and be confident that gamers will still play the lousy ones. They have to keep some good machines, otherwise they'd lose all the players who know what they're doing. But most of the machines will be bad, and most gamers will play them anyway. Heck, in Vegas even casinos and supermarkets have video poker, with absolutely terrible paytables, but people will still play them rather than going across the street to a casino where they can get seven times better odds. Go figure.