In order to achieve this, you definitely need to have impeccable on page SEO, you need to be active on social media, forums, other people's blogs in the form of valuable commenting, guest blogging, etc.
You'll improve your click-through rate in only one way:
Get more traffic to your web pages by any means possible, especially though by increasing the volume of qualified human visitors to your web pages. What is meant by qualified are that the visitor perform an actual search for what your web page primarily offers and arrives on your web page as a result of finding it in the search engine results. (that's not easily attainable by tag spamming alone incidentally)
by canadafred: thought I'd mention a pitifully poor SEO technique in brackets
You need to work on your snippet. As a rule, Google forms snippet from your page's meta description. Thus, meta description should be relevant to what is presented on a page and to what a user may be looking for. Otherwise, snippet will be formed from any excerpt of text Google will find relevant.
Also, add some schema to your page (if possible) to make it stand out on the SERP.