The key to dominate your fantasy football league is tiers. There is plenty of information out there as far as rankings and statistics of past years. The fun of fantasy football is you are your teams GM. Lists and rankings can help but you have to make the ultimate choice on your team. Prepare by grouping positional players into teirs. In this instance if you see a player in a higher teir and that particular position is begining to become depleated you can go ahead and reach for a certain player.
Another tip I would give is to spread your talent around. Do not go heavy with any one particular area. Always watch the waiver wire there is always going to be starting talent out there, keep your eye open for favorable matchups that could bust a players stats.