it's working out for me try urself u will see the difference. you can get do-follow blog list easily on dp.
Commenting is beneficial . See how : • Blog commenting either it's on do-follow blog or no-follow blogs can pass link juice. • Thoughtful and interesting blog comments will always bring human visitors and indirectly it will affect your rankings
it depends on whether or not you think google have implemented the rule cleanly. And whether they can deal with malformed nofollow urls, that kind of thing. They're not infallible - I remember when they used to have terrible screw ups with robots.txt files.
Yes, it is very effective.But you need to comment on do-follow blogs and the comment you make has to be relevant and useful.Comments are not automatically added to a blog, the owner often reviews them first.
my blog have more than 40k backlinks currently. It is only 10months+ blog and most of my backlinks is gathered from commenting. It is permanent and very helpful (dofollow in google).