It took me about 10 years to win a FF league. Since then, I've won about 20 more. A few observations....
- There is a lot of luck involved, but I wouldn't say it's 90 or 99% luck (like I've heard many people say). It's hard to put a number on it, in terms of a percentage, so I'll just say that there is a lot of luck/unpredictability involved. In most cases, if you field a decent lineup, anybody can beat anybody, on any given week. That said, your chances of winning are greatly improved if you're willing to put in the "work" like somebody else said.
- It pays to use the waiver wire. I almost always lead most of my leagues in waivers moves used. I don't think that means that I draft poorly, necessarily. Some people are either too cheap (in leagues where moves cost $$), or they just get lazy/disinterested (and don't make moves). Either way, it's hard to compete without using the waiver wire. There's just too much that changes in an average NFL season, whether it be injuries, suspensions, or other factors, to stand pat with what you drafted (unless it's a league where you draft only, obviously).
- The same thing can be said about trades, but it depends on the league. In most of my leagues, I've become pretty good (and pretty active), in terms of making trades. I tend to sell the future for the now (in leagues where future picks can be dealt), but not always. I guess that, as I've become more experienced with FF, I've realized that too much changes (from year to year, week to week) to assume anything. So, if I can improve my chances of winning this year, I'm willing to take a hit on next year's draft (which can be hit and miss, anyway). That's a different debate for a different time, probably, but my success in dynasty leagues has drastically increased since I've taken on that "win now" mentality.
- If you play in a lot of leagues, it increases your chances of winning at least one of them. But, that doesn't necessarily mean that it's good to diversify, in terms of who you draft. If you do that, you might not really increase your chances of winning, as much as you're just increasing your $$ spent. I tend to pick the guys who I think will do well, where I think there is value to be had. I'm in 17 leagues this year, and I made the playoffs in 15 of those leagues. I don't have Manning or Luck in any of the 17. But, I have a lot of Russell Wilson and Tom Brady, and guys like Brees, Rodgers, Roethlisberger, Cutler in about one league each. Likewise, I have no Charles, McCoy, Peterson (the consensus top three RB's), but made a lot of "value" picks on guys like FJax, Bradshaw, etc. And, it didn't hurt that I took LeVeon Bell and Antonio Brown a bunch. Plus, like I said before, the waiver wire helps (I snagged Asiata and Beckham anywhere I could, for example).
- I tend to stick to my own rules, in terms of who I start. In other words, I agree with the saying "always start your studs." But, if they're an injury risk, and you have another option who is 100% healthy (but maybe projected to score slightly less), I'll take the healthy player 100 times out of 100. There's nothing worse than losing in Week 14, 15, or 16 because your stud RB/WR (who was questionable all week) leaves in the second quarter, because they re-aggravated their high ankle sprain.
- If you're fairly knowledgable, make your own draft/lineup decisions (don't just follow some expert's rankings/projections for the year/week). It makes FF a lot more fun, and you second-guess yourself a lot less if it was YOUR decision in the first place (and not just something you decided from following a particular magazine, website, or writer). I typically make every decision based on my gut feeling. That doesn't mean that I don't look at other/outside influences, but I do so to affirm my thinking on a player. If it's way off, I look into that player/situation a little bit more, to see what I might be missing. It it's on (and mirrors what I'm thinking), I roll with it.
- Success in fantasy football is about playing the odds. In terms of who I draft, who I add/drop, who I trade, who I start, etc. Let's face it... Odds are the reason we draft kickers from NE or DEN, or kickers from domed stadiums. The same can be said for most other FF-related decisions. We're trying to find the guys that are going to score the most. Sometimes, it's as simple as who is more likely to score a TD this week. Sometimes, it's far more complicated than that.
Bottom line is this... It may sound like I'm in a lot of leagues (and I am), but I enjoy the variety. I'm in about 4 "locals"... all with people that I know from various parts of my past. Friends/family from one place, friends/co-workers from another part/place in my life, etc. The rest are just variety... A few redrafts, and a bunch of dynasty IDP leagues (that I've gotten hooked on over the past decade). So, I do it for a variety of reasons... To stay in touch, because I love football, and because I enjoy the competition/variety of being in various types of fairly competitive leagues.