Facebook Fan Page
Create a Facebook fan page for your website. Update info about your website, service, product and communicate with customers through this page. When people know well about you, people will become your fans and follow you. Facebook fan page will lead traffic to your website.
WordPress & Blogger
Create a blog page on WordPress or Blogger. You can promote your website by posting articles on these sites. Add links into articles. Good articles not only bring traffic, but also build high quality backlinks to your site. And backlinks will help improve your site ranking in Google.
YouTube
Life cannot be without YouTube. This video site has brought so much fun to our life. Why not create videos about your website, company or service and promote them on YouTube? Video marketing is quite popular now.
Pay-Per-Click or Search Engine Optimization
If you have any budget to advertise your websites, search engine optimization or ppc is absolutely good choice. Pay-per-click will lead traffic and orders soon, and search engine optimization will improve your ranking and bring traffic in long terms.
There are also a large amount of social sites such as, linkedin, reddit, etc. Whatever, keep in mind that you should promote your site where people are crowded and active.
There are so many ways to advertise your business website. You may take advantage of social networking such as Facebook and Twitter target the right people by simply adding friends with related interest. You may also post ads to free classified ads websites.
Or if you want a professional SEO company to do it for you with result-oriented seo service I strongly recommend Premium SEO Solutions.
I would look for industry specific sites that your customers may browse.
Example: If I sell "Athletic shoes" I may look at ESPN.com or if I'm more local ...I may look at my local newspapers online sports section to advertise.
Here are some general ideas:
adwords.google.com/ - Google Adwords
advertising.microsoft.com/ - Bing Advertising
searchmarketing.yahoo.com/ - Yahoo Search Marketing
Also make sure you have a Facebook FAN page for the business.
there are many sites where you can advertise a website to increase your sales, or to get Facebook likes, just choose a reliable and stable company that you can trust so you can boost your SEO. good luck!