Obviously, the more you bet, the more you will win for any given hand. With one exception, the win for any given hand and bet is proportional to the amount bet. However, notice that for a royal flush the win is 1000 for a bet of four coins and 4000 for a bet of 5 coins. The disproportionately high payoff of 800 per coin bet for a royal flush, with a five coins bet, is what economists would call an economy of scale. You will see this in almost every video poker game. If you don't bet the maximum number of coins, the cost of being short-changed on a royal amounts to about 2% of money bet, which is a lot. The wise video poker player will always bet max coins per hand.
6. Pair of jacks or better. Discard the remaining three cards. Sometimes players who are used to playing table poker want to keep a high-card "kicker" to the pair -- for example, holding an ace along with two queens. Don't hold a kicker in video poker; give yourself the maximum chance to draw a third high card, or even a full house or four of a kind.
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.