Are blog comments good for backlinks?

most blogs use nofollow so if so, then no

 

Blog commenting is a good way to build backlinks, comment on blogs that you care about and are related to yours, then you will get some traffic that is targeted and a few links out of it. By doing that you are contributing to someone else's website and may also cause them to contribute in yours.

 

Yes, at least you can get a traffic from your comment.

 

Yes exactly if the blog is nofollow and you are posting comments for getting link juice only than no,
and if you are wishing traffic than it's allowed to do make.
But there are many blogs with out nofollow you can post over there and get strong link juice as well as traffic also.
But whatever you post over there should be generic and content oriented,,, good luck,
in conclude i suggest you to do Posting.

 

is there a good place to find relative do follow blogs? or how do i know where to get them?

 

There are several threads on that in the Link Development forum. Do a title search for "follow" and most will show up.