Having lots of useful content on your web site such as informative articles, online tools, studies, etc will make another webmasters what to link to your web site knowing that you will not only help their site's traffic and link popularity, but adding content to their own web site. Sometimes you may even get webmasters that like your site so much that they will link to your homepage or to certain web pages that they think their visitors will find useful because this adds to the usefulness of their own site by providing useful links.

Type your keyword phrases into a search engine and wait for the results. The web sites you see on the first few web pages of the search engine results should be your main targets and should be looked at. Visit their site to see if you can find the site owners name and email them asking to exchange links, remember to email them at the right email address, don't email the email address that's for support.