Betting follows 5 simple rules and the better job done at identifying them, the better off we are.
Rule 1) Profits will always be eroded--Whenever you begin to get hot and start to win, profits are never maximized. You bet tight and try to protect your win. Conversely, whenever you are losing, the losing is maximized trying to play catch up. Any system you use works great when you are winning, but when it starts to lose as all systems eventually will at some point, confidence is lost and betting patterns are modified to your detriment. A system will only protect you if you play it exactly to a tee. Otherwise outside plays will erode system profits.
Rule 2) Murphy's law that governs the universe, applies to every facet of betting. If there's a slate of games you like, invariably you bet the losers and not the winners if you don't play them all. If you're following someone's picks or fading them---more often than not, you'll bet the losers and not the winners if you don't play them all.
Rule 3) Beware the Streaks--professionals make their money hitting 54-56% of their bets over the long term. If you're on a cold streak, it will continue. If you're on a hot streak, it will end. Winning streaks are invariably followed by longer and bigger cold streaks so beware the signs that a streak is coming to a close. They change on a dime and you don't see it coming until it's too late.
Rule 4) Slow train--When you get that gift .5 point cover or miracle win, it's a sign that the times are changing and not that you're luck will continue. You will be on the losing end of the miracle more times than the losing end so watch for it. It's a gift, take it and don't press.
Rule 5) Need to be contrarian--vegas information and trend data is just that, vegas data. You will not be in the know on the most important information and it's least likely to be readily available to you.
In sum, everything in the universe works against us. The better job done at managing these signs the more success.