Google loves blogs, and WordPress blogs specifically, so blogging is one of the easiest way to rank content high in Google and other search engines.
On top of that, you will often find that search engine traffic is some of your most targeted and best converting traffic, so it’s definitely worth going after.
But ranking high in Google is usually a slow process of building up great content and backlinks over time. Not only that, but SEO has shifted over the years. These days the most important factors are how people interact with your content; how much time do they spend on your site, do they share your content and how often do people pick your site when they see it in the search results.
Email marketing is super effective, but you need to build the list first and that of course requires traffic.
Paid traffic can be risky. If you have not had sufficient free traffic to your site to gauge your conversion rates, you could loose a lot of money throwing paid traffic to a site that is as dead as a dodo.