Balance is important
One common misconception is that you can still be successful by sacrificing one or two categories and focusing all your attention on the remaining ones. In my experience, it's very unlikely to win a league if you are at or near the bottom in any category. You may be competitive, but the difference between a title and a top three finish at best could be the one category you decide to sacrifice. You will need to be especially strong in most of the other categories, which is a challenge as there are always fluctuations over the course of a season.
This also goes back to my point about ensuring you have players that are producing, and not hanging onto underachievers. On paper, it may appear that you have a very strong team, which should dominate most if not all of the offensive categories. So, you might pay less attention to your goalies and focus all your efforts towards dominating offensively. What if your offense unexpectedly struggles? Is your goaltending good enough to keep you competitive? It's better to be relatively strong in most categories, than be dominant in a few and weak in others.
Make trades to improve your squad, not to win the deal
"Who wins this deal?"
How often do you see this question asked while you browse through a message board? The answer is too many to count. What I don't like about this question is that people assume that if you 'win' a deal, then it automatically helps your team. More often than not, it probably is a correct assumption. However, you can 'lose' a deal and still help your squad in the process.
This is especially important in rotisserie leagues. By paying attention to your weak categories, don't be afraid to try to make a deal to improve in a certain area even if you have to overpay slightly. This could also improve your chances against direct competition, especially if the deal helps your squad and could help you catch your trading partner in the process. If you can meet a need, then it doesn't matter if the deal appears to favour your trading partner. Your goal should be to win the league, not just the deal.
If you have maximum games, use them all but not too early
This is most relevant if your league has a limit on the number of games played at each starting position. If your maximum is set at 82 games, then you have to be extra careful not to use your bench players too often or you risk running out early. However, if you carefully manage your games played, either by sticking with your starting line-up most of the time, or use matchups, then you can be confident of not overplaying your games, while at the same time maximising your team's production. If you use your bench players on a regular basis, you may have the lead at some point during the season, but will risk maxing out far too early. I have yet to see a manager max out early and still win the league.
It could also be useful to stay under the games played pace if you have a few underperforming players, as a slumping starter doesn't help you very much. This could give you added flexibility in the latter part of the season when said players are back to their normal selves, and/or you have bench players who are on a hot streak. The key is to maximise efficiency and get the most out of your roster.
I won't go into a situation where a league does not have maximum games, as I feel it takes away much of the strategy and challenge that makes rotisserie leagues enjoyable. In these leagues, the most active (not necessarily the best) manager will likely win, unless his team is quite poor.
Take advantage of the rule that allows you to overplay your games at the end of the season
This is an official rule (at least in Yahoo), and it appears that many people are still unaware of it. By managing your games played throughout the season, you could be a position to use this useful strategy that could help you win your league if it's close at the end, or at least move up in the final standings. If you have one game remaining in a specific position (in Yahoo you will see a minus-1 in red), you can start the maximum number of players into your line-up the following day and receive points for all of them.
However, don't just pick any player, as you must closely monitor your categories and determine which (if any) you can increase your ranking with these moves. At this point of the season, it's possible that you will be too far behind or ahead of your nearest competition that it may not be worth it. If there is an opportunity though, make sure you take advantage of it.
Stay active and play until the very end
This seems obvious but it's especially important in rotisserie leagues. It can be a long and gruelling season, especially if you are working hard on managing your games, your players, being active in free agency and making trades. At some point, you may decide to give up as you feel like you have no chance to win. We've all been there. I would keep going because you might find yourself in a position to improve your standing at any time. Injuries, slumps, managers overplaying their games; these are common occurrences and things can quickly change. However, the best reason of them all is that we play the game to the best of our abilities, and it makes a league much more enjoyable with active managers.
This is "What I've Learned"; hopefully it's instructive for your own Rotisserie leagues. Good luck!
Stay tuned for my next edition: What I've Learned playing in Head-to-Head Leagues!