Go to this section: https://forums.digitalpoint.com/forums/search-engine-optimization.12/ then browse through the threads which is all about SEO. I'm pretty sure you'll get lots of informations on how to optimize your 6 months old blog.
You can start by naming everything correctly (e.g. images, links, titles, headings, alt etc) and adding fresh new content regularly. Keep your readers interested and the search engines will follow. Offsite promotion should come after the blog is ready and running as you like first.
Why not go with the old-school techniques that still works very well: 1. optimize your post titles. That's optimizing your title by using long tail keywords. 2. use keywords with semantic variations 3. use keywords naturally 4. internal link every post that can be related to an already published post within your blog. There are plugins for Wordpress blogs that can help you with internal linking. Good luck,