Google has a useful account on YouTube called GoogleWebmasterHelp that publishes short video answers to search engine optimization (SEO) questions submitted to them. If you have a website promoting your photography, then thinking about SEO can help you drive more visitors to your photography.
Here are a couple videos that are relevant to photographers:
How can a photographer’s image-focused site gain PageRank?
Takeaway points: include text relevant to the image(s) inside the img tag and around the image to help the search engine understand what the page is about. For example, you could include a description of the photo in the name or title tag of the image.
Secondly, allow visitors to comment on the image. This often leads to users describing some aspect of the image for you (i.e. “I love the light falling on the barn door”), which helps search engines understand what’s happening on the page.