I played in the open beta, so I had the opportunity to try out some classes, get a feel for the game, and decide what I wanted to do. I also started the game with a group of friends from FFXI, so we have a core group established. In that group, we tried to cover all the crafts/classes in the hopes to help one another out. My point is, I started at the Collector's Edition launch with a clear idea of what classes I wanted, and what direction to go in.
The moment I got out of the first CS in the game I started leveling my crafts and producing. I decided to hold off on battle classes for the time being, as I knew they would likely require overpriced low level gear to be able to level very efficiently. I played FFXI for a long time as a consumer, and wanted to be on the other side of that fence. So far it's paying off. (I'll just say my gil is in the 7 figure area) Being on the leading edge of the market was my goal.
I have to point out, too, that playtime is a factor. I work a full time job, but I had a 9 day vacation to coincide with the CE launch. That allowed me to stay ahead on my classes. Being among the first few to be able to offer a commodity item is not in the grasp of casual players, (not to say it can't happen, there are items in my crafting class that people higher in level than me have completely overlooked), but knowing what people need from your chosen gatherer or craft - and having steady buyers - can help you get ahead monetarily.
It's impossible for anyone (even the developers) to know exactly how the economy will form. Granted SE has taken measures, and learned a lot from FFXI, to have a better handle on it this time around.
All that said, my advice would be to choose a gatherer and crafting class that complement each other well, and work on them. Avoid spending too much gil on gear that marginally increases stats (a lot of progress can be made on the starter gear, and the repairs are very cheap). Keep an eye out for what people are /sh for, if you can make it, they will buy it! Build a network of friends and 'business partners' who can supply you with materials you need, that cannot be farmed or bought from NPC. Above all, don't stress yourself about it. It's a game! If you're not enjoying what you're doing, what's the point?
I started this character at the CE launch, and played for about 2 months. Haven't touched it since.