Backlinks are always helpful for a site. But it is very sad to find that most of the bloggers are not aware about the advantage and disadvantage of backlinks. Backlinks has both advantage as well as disadvantage but it is not always or in all cases. Some webmasters or bloggers creates numerous number of backlinks for their site to get pagerank but the fact google is looking for naturally created backlinks of the sites to give pagerank. Backlinks from 0 pageranked sites and google spam listed sites may results in the marking of adding the site in the list of spam. So before create a backlink the blogger need to check the seo stats and pagerank of the site. There are many sites which managed to get pagerank 1 from 100 backlinks and in another case there are many sites which failed to make pagerank from more than 1000 backlink. The reason is every backlink has its own value according to the site it is. It is possible to get pagerank 1 from 20 backlinks the simple method for it is select pagerank of 9/10 sites to create backlink. Of course it is not easy to create backlinks from such sites because the webmaster may protect their site from unwanted comments. Selecting different blogs itself for creating backlinks is a good option because most of the blog has easy commenting options so it is very easy to create backlinks, there are many blogs which has pagerank more than 4 so choosing such sites is always helpful.
Remember never creates backlink only because the admin will delete the comment for the unwanted use so provide some feedbacks or informations about the blog post will help to prevent the deletion of the comment. Creating backlinks on .edu and .gov sites will be more useful for the sites so try to create some backlinks from these domains also. Be careful that just create only about 7 to 15 backlinks is only necessary otherwise creating numerous backlinks without a limit will destroy the site so be careful when choosing a site for creating backlinks. So be aware that more than quantity quality is the key for getting pagerank by building backlinks. All the best.