How can I increase traffic to my website without paying anything?

• Promote it on social media.
• Add your website to your business cards, invoices, newsletters, etc.
• Answer questions on places like this.
• Give free seminars to educate the general population and ask them to visit your website for more detailed information.
• Provide detailed information on your website on a regular basis.
• Ask people on relevant, but not competitive, websites to link to you and start a link building partnership with them.
• Create an article on how-to websites that link back to your website.
• Join forums and discussions answering questions without selling yourself helping people.
• Create a useful much-needed tool on your website that people will want to use and link to.

There are many ways to do this. The only problem is finding the time to do it.