my biggest lessons learned in 2013...again, because sometimes I need to re-learn things at my advanced age....
1. Do your homework and research all year long, regardless of the type of league you are in. Re-draft, keeper, dynasty, auction, IDP, etc...., it doesn't matter. I have learned this lesson numerous times in my fantasy "career". If you slack off in your research and preparation, in any season, your results will follow accordingly. If you do everything you can to stay on top of as much information as possible, you will be successful.
2004 through 2010, I did as much preparation all season long as I possibly could. Success followed each of those seasons. In 2011 and 2012 I slacked off during the off-seasons and so did all of my teams. I had gotten complacent and had a "I'm damn good at this game and I can afford to slack off a little" attitude. I couldn't have been more mistaken.
Side note about research: While FBG is my main focal point for fantasy football information, it is not the only place I look for it. Take the time to actually click on the links that fellow FBG'ers post in their comments here in the Shark Pool. Take the time to digest that information. If it doesn't suit you, or you think it's hogwash, fine, but at least be objective....which brings me to.....
2. Learn to be objective and listen to, or hear, what others are saying. Don't just toss out someone's opinion if it doesn't match yours initially. It takes a little effort to open up your ears, but the rewards are worth it.
3. After adhering to both of the above, when it comes down to a "toss-up" decision, go with your gut feeling. I have been taught, and learned, this lesson so many times in fantasy football it's ridiculous. I have countless examples of this lesson exploding off of my 17-year fantasy resume. Every single year I have had a gut feeling on a specific player(s) or situation(s). Most times I follow my gut, other times I don't. Either way, my gut has been right 95% of the time. I have missed out on players because I chose to ignore my gut feelings, other times I have looked the genius because I didn't ignore them. Please note, you must follow the first two lesson's above for the "gut feeling" decision to have any credence.
I'm pretty sure you were looking for more 'specific' 2013 lesson's Joe, but these were the one's that instantly popped into my head.
Rody