To answer this very question we need to focus on the fundamental reasons why you want become a blogger. During the first 6 months you should forget the idea of earning money. In fact, earning since the very beginning may happen but it's not the rule. For this reason you should open a blog if you want to write about something. Something it's very important for you and that you want to share with others. Then, of course you can add specific posts to drive traffic but that's not what blogging is meant to.