1. Guest Posting: Make a list of authority blogs in your niche and pitch a blog post idea to them. 5/10 will accept your post if it's resourceful enough. Make sure you get link juice from the author box and link to relevant article of yours within the submitted guest post. Most bloggers would tell you the can only accomodate a single do-follow link per guest post.
2. Link Outreach: This depends on your niche. If your niche is a very popular niche, it might be hard to use this method effectively because most of the authority blogs in popular niche understands SEO so you can't trick them into giving you backlink. BUt if your blog is in the less popular niche, you can make a list of blogs ranking for your desired keywords, then send a message to the webmaster telling them about your newly published post, and asking them to tell you what they think about the post, and possibly link to the post in their resource section.
3. Link baiting: This one is tough, and you would need some tools but it works all the time. In a way, it is similar to the link outreach, but it's not done directly. What you do with this method is to find pages ranking for your desired keyword, then analyse them and check where they're getting their own backlink. Once that is done, you would then send an outreach email to those linking to them, telling them that you recently published a better, recent and more comprehensive post and ask them to check it out and link to it if they like it.
4. Web 2.0: This is a little bit of black hat, and I hope it's not against the forum rules to share information like that. With this method, what you do is create several 2.0 properties for yourself online, then buy all the cheap links to point to that web 2.0, then from the web 2.0 you can link to your site. It's a little bit technical than this, but that's the summary.
5. Link sales: There are quality blogs on fiverr that would offer to give you a link on their blog for $5. Some of these blogs are good. You just have to look in the right direction.
