Word-of-mouth is considered the very best marketing, because it is unsolicited. Here are some ways to encourage friends to share with friends, and use their network to promote your site.
Install “tell-a-friend” software to generate referrals. Such software allows visitors to recommend your website to their friends and customers. For this to work, it’s imperative that your website is informative and useful. Try and provide something unique on your
website. This could be a new product or a new service that would interest your visitors and encourage them to spread the word for you.

Create email newsletters and send these newsletters to your friends and customers. Always encourage readers to forward your email newsletter to their friends. Do this at the end of a newsletter, and you may inspire some readers to do it instantly.

Create attractive press releases with a link to your website and send these to customers and friends. Press releases are incredibly viral in nature. By providing a link at the bottom of the press release, you ensure that the reader can click on the link and visit your website. It is a good idea to submit your press release to publications that have the same type of target audience as you. Once you get some good press from the release, word-of-mouth marketing happens automatically.