Link Building - One of the most important factors of off-page SEO. Building authority links to your websites increases your link popularity. Link popularity is simply the number of back links that your site has. You can use the free external links tool in Google's Webmaster Tools to check which pages on your site have links pointing to them from other sites. Remember, higher link popularity = higher authority and visibility in the search engines.
Reciprocal links have been de-valued by Google. So, one of the best ways to build links is by ensuring that your site's content is not just original but also informative. This is the #1 strategy that in itself invites other webmasters to link to your website.
Article marketing - Quite literally, the Internet is overflowing with article directories. However, you must consider only those article directories that have good authority and can help you to generate targeted traffic. When you submit an article, you'll be given a 'resource box', which you must use to introduce yourself, your company, and share your site's URL. Since many of these article websites have a high authority, links from these sites would pave the way to increasing your own website's authority as well. Many of these article websites also allow other webmasters to take a copy of your article for use on their own website, as long as your resource box remains unchanged.
Press Releases - Similar to article marketing, press release marketing involves adding your press release to press release directories which have good search engine authority. Again you can add links to a resource box, and in some cases you can embed links within your release. Press releases also have the added benefit that if your release is newsworthy enough it could also end up being printed in off-line media such as newspapers and magazines too.
Forum marketing - Forums are on-line community spaces dedicated to a particular subject of interest. Find some good, reputable forums dedicated to your website's subject and join them. As a member, you'll be able to post messages and reply to other members' queries. Quite often you will also have a signature box that shows up in each of your posts. Use this signature box to advertise your website and paste its link. Posting significant messages with your website URL will help you in increasing the link popularity for your website.
Advertise at Craigslist classified websites and present a novel way to enhance your link popularity. Both are very popular websites with a high authority! Having links from these classified ads websites could give you a boost. All you need to do is post your own ad under the right category.