Blog commenting is one way of doing backlinks for your site. I think it is good that you do blog comments on blogs that are related to your site.
Yes, it is one way of doing backlinks for your site.
You don't necessarily need them to be related to your site but it is good if you do find related sites.
High PR comments are good, if your doing it manually you don't really need to worry about auto approval either. If you write something that clearly shows you read the post and add something it will get approved. This can allow you to get some really high PR backlinks on pages without many out bound links. These have gotten me first page results alone.
You can also track down your competitors backlinks and manually comment on blogs they have links from.
Rank tracker has a free tool you can use to track competitors.
Good luck mate, try and spend a hour a day building 5 or 10 links for a month, I am sure you will see good results if your niche is not way to competitive.
I also blast the blog pages with my backlinks with Xrummer, you can get this done for $5 at fiverr.com. Keep that in mind if you want, you will want to create a excel file with all the URLs that have your backlinks.
Make it look natural when you make links, don't do all the same anchor text, partial match anchor text mixed in helps a lot.
Have fun link building!
Cheers,
GlobalP
