Greetings, Johnny! Foremost, it's totally personal preference. Follow your heart. Choose the job that sings to you. That said, since you are asking for recommendations here anyway, I'd probably go for a second role. Dragoon is DPS, so that leaves tank and healer.

As for early levels, I'd suggest the hunting log till you can do roulettes. Again, though, whatever you find the most fun is the real answer.

Beyond all that, I'd personally elect to finish all the main story FIRST.