for do follow link forum and blog is the best platform because these sites give a do follow.. link.. but some forum site not provide a do follow link..

With blogspot, sometimes your comments are still nofollow backlinks because dofollow backlink function was blacked by the owner of blog.
So that, you must check that blog allows dofollow or doesn't.

hello
if you want do-follow links, make profile on orkut and put url in bio.

Do dofollow forums with signature option to get dofollow backlinks.

I found commenting on blog post very hard and time consuming. If you are not genuinely on the blog it just looks spammy