As for the record in the present year,Google has penalized several sites by manual action penalty. The reason behind this that they have unnatural links outgoing from their sites. So I am afraid right now that some of my blog posts contain outgoing links. It is not that I am selling links but its best for the post itself to provide some necessary additional information. Should I make all my links no-follow? or, should remove those links?
This is a common fear in every bloggers mind that 'having hit by manual action penalty'.
I will recommend you that if your are providing do-follow links from your page then make sure that they are super relevant to the content and also they are utmost necessary. Maximum limit you should maintain is 2 per post, otherwise make them no-follow.
If you are providing some kind of list, product reviews, or posting any kind of personal opinion about any other post (person and/or community) then always make the links no-follow.