If you want to get organic (free) traffic to your blog, you need to understand SEO. particularly Google SEO. When you are thinking about what to write you need to understand what people are searching for, then write for those keyword phrases. Otherwise you will be writing for no-one.
Some people prefer to use social media (Facebook, Instagram, Pintrest etc) to drive traffic to their blog. This is a good idea if you don't want to get into SEO, although this is not something we cover here.
If you are in a hurry and have a little cash to burn, you can use paid advertising to drive traffic to your blog. Google or Facebook ads are the favorites. I prefer to use Google ads to drive traffic to blog posts. The research for this is similar to organic SEO. I would also recommend that you use paid traffic to build your email list or sell something or else you could burn through a lot of money without seeing a return.