Things to consider for this first stage would be to check Webmaster tools, check Google index, check your backlinks, check your robots.txt file and check your WordPress settings. These checks basically show you how Google is finding your website and highlight any issues they may find.
These may include too many pages, too few pages, any hacking issues etc, basically the kind of things that Google will shut your website down for.
Once the foundations are set, then the second stage activity would be to boost your SEO capability by using the Yoast WordPress plugin. This gives you a tick list of SEO boosting options, like focus keywords, SEO titles and meta descriptions for each page of your website. Come and have a seat on the sofa if you are interested in search engine optimisation in Doncaster.