The final strategy you can employ to improve traffic on your website is to use search engine optimization to improve your organic rankings. Improving your website's ranking for certain keywords can bring a significant amount of traffic. Since a major component of improving your rankings involves link building, you can kill two birds with one stone. Adding a link for SEO purposes can often draw raw traffic from that link as well.
As important as it can be to improve your rankings for a particular search phrase, it's equally important to improve the number of different terms you rank well for. For long term survival and growth, it's better to bring in 50 visitors from 50 different search phrases rather than 50 visitors from a single search phrase.
When you increase the breadth of the search phrases you're ranking well for, you are accomplishing the same goal as investors strive for when they diversify their portfolios. By diversifying where your referrals come from, you'll take a step towards protecting your website from dramatic traffic declines. Your rankings will move up and down as algorithms change and competition stiffens. Protect yourself by diversifying.
Search engine optimization is an involved field and there are forum posts all over the Internet from webmasters who have lowered their rankings while trying to improve them. If you choose to pursue this strategy, take your time and be prepared for a few set backs along the way as you learn.
Any of the three tactics discussed in this article can help you increase traffic to your website. But using all three in concert will be most effective because diversifying your traffic sources will help your traffic patterns remain stable over the long term. Keep in mind though, increasing website traffic is only an means to an end. If you're trying to improve your sales for example, you could make some improvements to your website to help improve conversions amongst your existing visitors. But that's a topic for another day :)