Google does not really qualify the no follow links as a criterion in the search ranking value. You can freely have your no follow link on blogs and other platforms and it would not have any effect as such on improving or affecting your page ranking. So basically the no follow links do no harm and they certainly do not cause any penalties from Google. However, this does not mean that these links are useless.
Those websites that have a lot of traffic with the links on them irrespective of the fact that they are no follow links can still continue to send the traffic. The traffic so generated can be very helpful in lead generation, improve conversion rate and also encourage the other websites to get themselves linked to yours barring the no follow attribute on the link. When we talk about links with respect to social media we are merely creating awareness about the content on the concerned website. It is this awareness that will lead to many more link building prospects and further spread the awareness about the programme.
When to use the No Follow Links
No two links can be treated equally. Most of the sites have links that are not so important or the links that do not change at all, like an About Me page for instance. Making use of the no follow tag for such links would be one of the most appropriate ideas. The no follow tag should ideally also be used for the paid links and the content that cannot be trusted. If you host certain text link ads on your website, ensure that they are tagged as No Follow.
However, it is to be noted that some of your site leaks some of its Google Page Rank to the other sites even through the no follow links. Thus, it is advisable to have only a few outbound links from your website especially if it is your homepage for SEO purpose unless of course, you are trying to promote the website you’re linking.