Seo is the best way to drive traffic to your website or blog. First once you have good seo and your site is ranked well in google and other search engines you get FREE traffic to your site. Paid ads can drive traffic to your site but you pay for every person who clicks on the ads.
Seo sends free traffic so you make more money off each sale or signup than paying for multiple people to go to your website and getting a sale. The best free way to get website traffic to any website or blog is SEO and you make all the money and pay nothing for the traffic.
The free website traffic is 24 hours a day and cost nothing. You have to keep paying google to advertise your site and still pay if no one ever buys something or signs up for something.