The best thing to do is take your time and find quality blogs which do not accept any comment. If the blog is well moderated and you take your time to construct an intelligent reply, you can get a lot of traffic from just one comment.
Originally Posted by johnysumner
That's correct! Moreover, a dofollow blog will give your website boost for SERP.
But no-follow blog comments can be helpful too. If done with quality, you can probably get traffic from it.