Discipline is the most important thing you can ever bring to the equation. Bankroll management is where this discipline factor comes in big. Never spend more than 5% of your bankroll on any single match-up no matter how much of a lock you reckon it is. Bet 2-3% as a general rule, and go all the way up to 5% on games you feel strongly about. Never bet more. Always remember that you aim to make money in the long-run, and in order to be able to do that, you have to make sure you stay in the game.
Another very important thing you need to understand is the nature of the game of sports-betting. For that though, you first need to know what mathematic expectation is.
Let`s suppose we both bet on a coin-toss. As long as we both bet the same sum (let`s say $1) the mathematical expectation is 0 for the both of us. The odds are 50-50, and if we play on forever, we`ll never win or lose anything. Now then, if I bet $2 on the same toss and you bet $1, this is how things are going to shape up: on ...