From where they come is not as important as their flow.
One of the crucial question is – What is more important Visitor, Reader or Subscriber??
Remember Visitor can be Reader, Reader can be Subscriber; Subscriber may not be reader, Reader may not be subscriber.
All permutations and combination are possible. In order to drive traffic you must have reader and those reader which are very appreciating normally turns into Subscriber.
The new Visitor who are reader, if feels that your site is having excellent content can turn into subscriber or you can convert them into subscriber by offering them to register and giving them some free material like e-book on SEO,
Traffic Management or any such by which you can attract them to subscribe.Online earning depends on them only.
Adsence or brite or any PPC revenue generation plan depend on them.
Always remember that all visitor can’t be Reader ( Your bounce rate will let you know this ) and all reader can’t be Subscriber. If you want to do E-Mail marketing you must have subscribers and for traffic you must have visitor.
Visitor are attracted through many sources of Traffic, Organic visitor will be more of visitor than reader and subscriber while non organic visitor will be more inclined towards becoming your blog reader and may also convert into subscriber.
For making reader a subscriber you must make them feel that the content of your blog is what they need. For this your article Heading must not be only SEO friendly but also be eye catchy, like 5 best SEO software, The last suggestion you will want to try etc. Show your expertise and confidence in your writing to make them reader from Visitor and add the stuff like free e-book, exclusive material to make them subscriber.
If you differ from the point do let us know you view.