04-21-2015, 04:20 AM
Forum links and links from blog comments are basically no-follow so they don't pass any kind of link of juice and hence no positive effect on your SERP's. And for the question that they can hurt your site or not I will say that if you are posting comments and posting topics & articles in forums which are relevant to your niche then its okay. As long as you do them manually and make the incoming links relevant not only from the pages they are coming but also to the pages they are referring, you are good till then. Forum posting and blog commenting if done wisely then can also build a good authority of yours in your niche.