This guide here will explain how to create the link, then you can post it where ever you'd like. My favorite place is in the service follow up email.
Make Quality Content
If you are going to give something away for free, let it be information. Search Engines love it AND it gives you something to post on Facebook and other social media. Try to schedule this with some sort of frequency.
Have a PROFESSIONAL code your site. We know its tempting to have your school age friend put a website together for you, and while the may make something beautiful for cheap, the world of SEO is a competitive one and this is an area where experience counts.
Handicap Accessibility is an example of proper coding. You will be penalized if you do not provide.
Make is FAST - Sites that load faster climb higher in the rankings. Most search engines want to provide a quality browsing experience.
Make it SECURE - If you are capturing any information from your customers (this includes a contact form) than SSL is highly recommended. Not having it may even trigger security warnings from your visitors browser. Nothing will make them run from your site faster.