You can write articles about your industry and post them to article websites. You include a resource box with your website URL in it. The article websites distribute your article through the web with the agreement that anyone who uses your article has to keep it intact including your resource box.
Here’s a link for a site that has listed a lot of the article directories. If one of the niche directories is a good fit for your business, I would start in that section.
http://www.arcanaweb.com/resources/article-directories.html