Blog commenting

Commenting on blog and generate back links depends on the value of page rank as the have more value that is not that mush easy to get approved your comment by site owner to create back links from blog commenting you can search in this way or go for blog search while commenting make sure that you are commenting on the related site or go for this
Keyword inurl:blog in search engine so that you can get the best from Google
The links you have generated either by blog forum etc.., they are two types

1. No follow
2. Do follow