A lot of people are asking on how to build authority links to their websites so they can rank well in search engines and gain a lot of traffic. Building backlinks is a great way to increase your PR and have authority over other websites when ranking in search engines. Also, you should put in mind to choose those of related to your website and are quality sites, it's just like "Quality over Quantity". So, here are some methods on how to build authority links and increase your link popularity:
Social Communities:Social bookmarking  is one of the most common way to build easy and quick backlinks to your websites. There are a lot of social bookmarking sites to choose from so you should choose wisely and not use all of the to save time, you should choose those that are dofollow. Social Bookmarking is not the only option, you can also join a forum and post the link to your website in your profile and get backlinks from high PR websites. You can also use social communities that allows you to make a free blogs and build some backlinks to your main site.
Forum Commenting:Forum commenting is another great way of building backlinks to your website via your signature. Some forums don't allow signature so choose those forums that allow you to add signatures so you can put a link to your site there. Some best forums that i know are Digitalpoint,southpoint, and there are a lot of other forums that you can choose from. Some doubt this method and think don't have much value but a lot of websites are ranking very well because of their large amount of backlinks in forums so i know that this builds authority links.
Blog Commenting:I don't use much blog commenting because i prefer joining social
communities but blog commenting is also a great way of building backlinks to your website, especially if you are commenting on a high PR website. You can also get a link from their homepage if the site offers a "list of top commentators" in their homepage, so comment a lot so you'll be in the list. Be careful when doing blog commenting, you should make sure that your comments are valuable and related to the post you are commenting so you'll not get spammed.

Hi,
The processes you discussed in the post among them, forum posting and blog commenting considered as the best, quality and niche links and having weight-age from SEO perspective.

Nice Tips.. thanks for share these methods with us.

Thanks for letting us know about the sites that allows forum signature link.
Thanks again.