to build links you need to exchange links and create content that links to your site , this will make others link to you for the content! Or really drill down your SEO terms and find a niche that fits well.
Write quality blog comments - Blog comments have a bad rep in the blogging community. Why? Because of the spam bloggers have to deal with every day. But your blog comments don't have to be like this. Blog commenting has the potential to give links that are just as powerful as links from guest posting. By writing quality blog comments on dofollow blogs, you're giving yourself powerful links that are within quality content. My biggest tip for blog commenting is to add to the discussion. Whether it's to agree or disagree, all blog comments should add to both blog posts and previous comments.