A lot of

's
I've been playing FF since '96 and was pretty bad at it for the first 4-5 years. Didn't get that beginners luck. Now Im in 4 competitive leagues, sometimes 6 (I'll only play in 12-16 team leagues) and am pretty much a given for playoffs and sometimes win the whole thing.
What started working for me was becoming hungry for info, studying for drafts (read VBD) and always concentrating on loading my team with as much depth and potential as I can.
Another is getting good at trading. All player values have an eb & flow throughout the season. Having an expendable player go off or getting that player splashed on the front of CBS Sportsline is usually an indication some guy is gonna over-value your player because of one good week or injury (Brandon Jackson '10). Strike while the iron is hot and deal him. 2 for 1 or 3 for 1's are the best (you getting the 1). You'd be surprised how much you can Improve a position with these kinds of trades, sometimes getting their 1st, 2nd or 3rd round pic. But what isn't considered in the makeup of the deal is the added value I see when I make these trades ...more open roster spots. Now I have another open slot or two to mine the WW. That's gold to me cause I feel like trading and finding talent is my strength.
My other secret is kind of like a theory I have. Usually when teams draft QBs early, some of these teams are weaker than the rest of the non-QB drafting teams. By week 6 they may be 2-4 or 1-5 and figure out their team is gonna sink unless they can make a move. I love targeting the slow-starting team's QBs because I can usually give them a productive mid-tier QB and a mid-tier WR or RB and take their top-5 QB. it's an easy sell and makes a lot of sense to them on paper. It's strange, but I do this often and it works.
Don't be that guy that makes insulting offers all the time though. Know your team strengths, look over rosters, find their holes and see if you can fill in for them. Explain your rational and why it makes sense for them to make this deal. If they say No, be thankful for them considering it and keep in touch because they might get back to you the next week when they realize you were right. If you're a ####, they'll write you off out of male pride.
I think something that helps tho is that I'm a natural salesman and do just that as a job (business dev). So I love going after a deal, bartering and making it work.
Best of luck!