Link building or the process of getting backlinks to your website is very important because other than to increase referral traffic to your site, it'll also increase search engine traffic by increasing your site's PageRank. Link building is therefore the most important step in increasing your website's traffic.
Link bait as the name implies is anything in your website used to lure people to link to it. This is the most effective way to increase backlinks to your website, and is probably the easiest.
Link bait can range from good contents to online calculators that you created and host it on your website. If people find it interesting enough, they'll share it on the Internet and give you backlinks.
If you run a few websites and at the same time run a blog, you can blog about the other websites you're running. You can start about talking about the websites in general, and then maybe blog about some recent updates of the websites.
Blogs normally allow you to add your website's URL in the comment section. If related to your comment post, you can also link back to your website or any part of it in the comment section.
You can post a new forum thread or reply to existing ones in topics related to any part of your website, linking to it as source or reference.
In some forum and mailing list, you are allowed to create signatures that you can use to create a link back to your website.
Social media like Twitter, Facebook and Stumbleupon is a great way to post about anything that you have on your website. If your post gets shared by others and goes viral, you'll see a spike in your website's visitor count.
Social bookmarking sites allow others to view your bookmarks. Adding your own website and articles to social bookmarking sites would give you some extra backlinks.
Articles submission websites such as Ezine articles allow you to submit your articles to be published on their site. They also allow a link back to your website as writer's profile or as source links. As these websites normally has high search engine ranking and high user base, having a backlink from these sites could give you a traffic boost.
Particularly popular in blogging sites, you can ask your friends to include a link your website from theirs, and create a link to their website in yours if they require to.
If you have some extra budget, you can advertise on other websites that provide advertising space. You can also opt for PPC (pay per click) advertising such as Google AdWords.
Web directories are websites that allow you to submit your website to be included in their directory of websites. While most are free, some require you to pay for the service. The popular web directories such as dmoz and Yahoo! Directory are hard to get approved, but it's worth trying as it could give you a boost in search engine ranking, if not just referral traffic.