The main aspect of successful sports betting is knowledge. Knowledge is certainly power, and the more you have, the more bets you may win. The key to winning bets is feeling at ease with your betting decision. The best way to feel confident is always to conduct a little shopping around, learn about the teams, players and coaches, and then make your decision.
Once you've done some research, you will have concrete reasons as to the reasons you are betting in this way. This is much smarter than betting along with your gut instinct. Your gut feeling might win a bet every now and then, but in the long term, you will surely end up losing more bets than won by you.
The best way to determine you have done enough scientific studies are to explain your reasoning in making that particular bet. When the argument you're making for one team over these guys weak and never backed up by much evidence, this isn't a bet you should place. However, if your argument is powerful and persuasive, you need to feel very certain about placing that bet. The more bets you set when you are confident, the greater bets you will win.