Even though it's an MMO, it's very solo friendly. As you progress through the story, just focus on a DPS spec, tank and heal specs are for group content (which you probably won't be doing for a long time) but will slow down how quickly you get through the story. Speaking of, each class as a unique story you play through. I would suggest going through all the stories, you get fun little account unlocks and there's small little ways each of the stories connect to each other. Finally, and this may be something you might not like to hear, I would STRONGLY suggest subscribing for a month or two. The f2p restrictions can be aggressive, and being a subscriber completely removes them, but then reverting to "preferred" (an account that has previously spent money) has less restrictions attached compared to a fully f2p account. During those months you are subscribed you can buy permanent account unlocks that will make the preferred status a lot more bearable.