This is an easy question. Score more points than the other teams!
Anyway, stay on top of your team all year. Draft well, trade from areas of strength to address your weaknesses, scour the waiver wire for hidden gems, and check in here often to learn about updates/position battles/injuries earlier than your leaguemates.
Also, in the week or so leading up to your trade deadline, figure out who your main competitors are and where they are vulnerable. Taking a point or two from them is as good as gaining a point or two on your own. For instance last year I realized that there were three teams that had the goods to win the league. One of them I was fading, and I thought I could catch him without doing anything. But another had a second place hold in Saves. I traded Randy Johnson for Dempster, Ryan, and Batista. I could have gotten more talent for Randy had I traded him to someone else. But over the last month and a half those three guys pulled me into the race for second in saves. When Billy Wagner got me a save on the last day of the season in a game they won 10-3, I broke the tie and won the league by a half point.