If it's your very first toon - I advise not to get powerleveled. You'll miss everything you get along the way that will help your character out much much more than just getting to 70 asap.
Follow your journey chapters to get your gear for that character. Seriously, once you unlock them, which is pretty easy, you'll level up pretty quickly.
I haven't even played through the story! Adventure mode is open from the start, so you can jump around to do what you need to do.