You will want to create search engine optimization image titles and tags for any images that are directly relevant to the content you are creating.  When a user searches for an image that is contained on your website, the image will link to your website.  Your website will be result in image searches, without the  user actually searching specifically for your website, product, or service.  Your title will be in the image link and can spark the visitors curiosity or interest in finding more out about your web page.  You will find that this greatly helps you achieve the results you are looking to find.