Optimising a website is a systematic process these days. Identify your keywords, optimise pages on your site for those keywords and build links from external sites. However before you begin, consider measuring where your are. To measure your starting point,  you need some analysis tools such as Google Analytics or Stat Counter.

Further more, I suggest that you have an SEO audit of your website. This not only tells you where you are, but makes suggestions regarding what you need to do. Click for examples of some video audits that we have created in the past.