Backlinks really matter for any site's ranking. Backlinks are the recommendations like a best doctor you try to find by asking others, You always choose the doctor who is recommended by more people, Same thing google does for ranking of any site. More backlinks means more recommendation of your website by others, So try to get more relevant backlinks related to your niche.
How to Get Quality Backlinks Without Guest Posting ?
Create web 2.0 sites
Create 10-15 web 2.0 sites and write some important things on them and put the link of your main site in the articles. you can choose Blogger, Weebly and Hubpages to create web 2.0 blogs. After writing a good article in web 2.0 sites share those articles on google plus and facebook. Do social bookmarking of those articles. I got 3rd-5th position in google search for one of my blog by using this method.
Find Relevant Sites to comment
Commenting is one of the best and easiest method to get backlinks. Putting a quality comment in relevant site will boost your SEO than putting a comment in irrelevant site. To get quality sites you can use dropmylink.com, Here you can put your keyword and by selecting proper places to comments hit search button. You will get a google search result page with relevant sites where you can comment.
Dofollow Vs. Nofollow
Bloggers and webmasters say that dofollow links only increase ranking, It is not true completely. Nofollow links also increase your SEO juice, You can also comment on those blogs which do not provide dofollow comments.
CommentLuv
Cooment Luv sites are best places to comment, Here you can link your one article with title, Which is really a best SEO tactic. When you are using Dropmylink.com, Always choose commentLuv premium option to find comment Luv blogs for commenting.
Contact Webmasters
Some blogs have been removed or rebranded at this condition they have change their sites domain name, You have to find such sites and create list of such sites. Now find those sites which are already giving backlinks to those expired domain, Contact those site's owner and request them to remove expired links and replace it with your links. Using this method you also can get good backlinks.