Link building is not just throwing your link any place that you are allowed to place a link . This will not help the cause and will even lower your site’s link popularity. Few important things should me kept in mind as you build links for your site are :
1. Make sure you have a site worth linking to. You must have unique or valuable content to make your site linking worthy.
2. It is wise to spend few hours a week on building links. Manual link building may be a slow process and tedious too, but automating the process just doesn’t get the same results. The search engines are smart enough to be suspicious when your site suddenly acquires thousands of back links over night.
3. Varying your anchor text is advised .When you generate links from within a sites content , it appears more natural looking to search engines. Search engines will also notice if every single one of your back links reads the something.
4. Do not comment on forums and blogs just to throw your link there instead add something of value to the discussion, or you’ll just end up getting you account banned.