There are tonnes and tonnes of images out there in microstock sites. Just do a search for images from the main players such as Shutterstock and Dreamstime and you will see for yourself the quantity of images they have and the number that is added every week.
Having said that, how do you, as a contributor, increase your sales by improving the chances of buyers finding your images in the first place? The most important step is to get your images to appear in search results.
It is mandatory that we have to add titles, descriptions and keywords into our images before uploading them onto microstock sites. But, note that for the same keyword, you are competing with thousands, probably tens of thousands of other images with the same keyword, so the chances of your image hitting the bottom of the list is in fact quite high. And the fact is, if your image does not even have a chance of appearing at the top few pages, the chances of it getting sold is near zilch. The truth is, more exposure leads to more sales.
How, then, do you improve your image search rankings?
The answer is to focus on long tail keywords. By long tail keywords, I mean keywords that target the less competitive niche markets compared to the highly competitive keywords. For example, a short tail keyword may be something like “business man” while a long tail keyword could be “business man black suit”.
When you compare these 2 phrases and do a search for them on microstock sites, “business man” returns much more images than “business man black suit”. The key here is to include keywords that describe certain (but related!) details of your image. Your images might rank lower from searches on the broader keywords such as “business” or “man”, but for buyers who know what they are looking for, they are more likely to use long tail keywords and your detailed keywording will make a huge difference.
For more information on long tail keywords, refer to this article which provides an in-depth explanation.