Search engines currently base relevancy primarily on linkage patterns. Who links to you and how they link to you are what determines where your site will rank for competitive search queries.
Few steps for Link Building:-
1) Make sure your site has something that other webmasters in your niche would be interested in linking to.
2) When possible, get your keywords in the link text pointing to your site.
3) Register with, participate in, or trade links with topical hubs and related sites. Be in the discussion or at least be near the discussion.
4) Look for places to get free links from.
5) Produce articles and get them syndicated.
6) Participate in forums to learn about what your potential consumers think is important.
7) Issue press releases with links to your site.
8) Leave super glowing testimonials for people and products you really like.
9) Leave relevant comments in blogs that do not send their comments through redirects.
10) Sponsor charities, blogs, or web sites related to your site.
11) Consider renting links if you are in an extremely competitive industry.
12) Mix your link text up, if you can.
13) Survey your vertical and related verticals. What ideas/tools/articles have become industry standard tools or well-cited information? What ideas are missing?
14)All the links pointing to your site should not have the same exact link text as that could be a sure sign of link spamming. You want to mix it up and use different text links from different sites. This will make it appear as natural linking to search engines.