Link building is the SEO practice of obtaining links from external websites to your own to improve both direct referrals (i.e., people clicking on the links), and search engine ranking. Link building is all about increasing your site link popularity.
Website Crawler goes to a site again and again whose ranking in a search engine is high. You can verify this fact by putting your site on a high-rank site. If your site link is available on a high-rank website, then you have 99.99% chances that your site is indexed within 24Hrs.
There are various ways of increasing your website link popularity. You can follow the tips given below, which are easily doable.
Submit your site in popular search engines manually. Do not go for automated submission.
Get your site listed in Open Directory Projects like dmog.org, yahoo.com. Getting listed in these directories gives a boost in link popularity and improve search engine ranking in other search engines.
Provide high quality content so that anyone would naturally link to your site if you are featuring what they want, and that is not available anywhere else.
Leverage your personal relations with other webmasters. Put your site link on their sites. One-way links often count for more than reciprocal links.
Participate in Link Exchange Programs. Find top 20 sites doing the same business and contact them for reciprocal links. Link exchange between unrelated sites might affect the ranking of websites in the search engine.
If you are subscribed in a forum and the forum does not have any restriction to keep your site link as your signature, then it can help you to increase your site popularity.
Submit your site to bookmark sites like DIGG and Slashdot. Before submitting, please go through their spam policy.
Write good articles in blogging sites and give a few references of your links within that article.
Keep providing good content to your site visitors. Try to keep them busy on your site. If possible create forums, newsletters, blogs, etc.
There are other ways, but you need to spend some dollars to go for such alternatives.
Buy a place on high-rank website where you can put your link.
Subscribe for Google's AdWords program to drive traffic towards your site.
You can go for alternative advertising option to increase the number of hits on your site, which can result in your site link popularity.