Been playing Dynasty FF since 2000, experience has taught me plenty of lessons I'd teach the 2000 version of myself if I was just starting up today:
For your first Dynasty League experience, especially if you're playing for money, I'd strongly recommend joining a start-up. I like the idea of one's first League being one you see develop/have a hand in developing, from the ground up. Back when I got started, it seems like this was the only way to join one, as Dynasty was in it's nascent stages. I was invited to join a start-up that already had the structure in place, so my first 'League Activity' was the initial Player Disbursement (Draft), everything else had already been decided by the Founder. FWIW, he had done a great job with this. I think now that it would have been even more fun to have had a hand in that, but I don't regret how things worked out because I was lucky enough to join a League with a strong Founder.
The following year, I and another member founded a League that I continue to run to this day, still going strong. We based it largely upon the League we started in, but tweaked it to our preferences. The structure of the original League was very well thought out, and provided us a tremendous framework to build on. We've continued to tweak over the years, and while the League is very different than the original, if you peel back the onion, you'd recognize the skeleton as a close relative of the original League.
I also strongly recommend (echoing Gally's post above) starting/joining a start-up that plans to use an Auction as it's initial Player Disbursement. That was the first rule we put in place when we started our own League, the year following joining the start-up that disbursed players using a traditional Draft. We strongly felt one of the keys to encouraging Owners who were also largely new to the format, to invest long-term into their Teams - if they had as much of a hand as possible into crafting their initial Rosters/incorporating their own personal philosophy into building their own unique Team that reflected them personally. We started with 14 Teams, eventually expanded to 16, and going into our 17th Season, still have 8 of our original 14 Owners on board.
I only play in money Leagues; it's just how I'm wired - I just can't invest that much time/energy/effort in anything without there being a financial risk/reward being the carrot, so keep that in mind when I say that, especially with a start-up, as much as it might be an ideal that the League is going to continue in perpetuity, you never know how these things are going to play out. With that in mind, I'd recommend building/managing a Team right out of the gate that's designed to 'win now, win often' - bankroll as much as much real cash as you can right away. I've read that most Leagues. like small businesses, fail in the first few years after start-up. By winning early, you not only maximize profit through the riskiest time for the League, you can finance developing a consistent contender by already having several Season's worth of Entry Fees paid in the form of 'House Money', so you can go about doing it the right way, without the pressure of filling a financial hole you're digging right from the start. One of the reasons people quit is because 3 or so years in, they're now out '$x', and they start doing the math of figuring how much they have to win to get back to the break-even point, much less be in the black, and that starts adding pressure to their decision making process, and the League starts becoming less 'fun' and more 'work', and they opt out rather than seeing it through. I didn't go into our initial Auction with winning Year 1 in mind, I just opted to buy Players I knew more about, and let the other Owners spend on Rookies, or younger players with shallow resumes...but I wound up winning Year 1, and Final 4 in Year 2, which effectively paid for Years 1+2, plus almost 6 more years of Entry Fees right out of the gate. While that didn't necessarily translate to consistent, continued success, it did translate to a plenty of fun. By nature, I'm personally prone to riskier behavior when playing with House Money, and I explored several strategies I might otherwise not have employed (to varying degrees of success/failure), had I been focused more on backfilling a financial hole. Having that freedom, and exploring those strategies improved me as a Player, tremendously, and I'm still 'in the black' over the life of the League, albeit following a pattern of win/suck/contend/repeat, rather than consistently doing one or the other, more often than not. I've certainly had the opportunity to consistently win, but with plenty of 'real' money winnings, I'm finding it more fun to take chances/experiment with strategies, ideas, harebrained schemes, etc...