My experience with email marketing has been with the use of sending out a newsletter to those who have subscribed to a client's list. If it is done in a way that does not seem pitchy, people tend to forward the newsletter and in turn, more folks sign up for the newsletter. Giving you more potential clients to market to...
I use iContact and AWeber. AWeber gives you more tacking options so that you can really see where your traffic is coming from. So, if you have opt in forms on all your social media accounts, AWeber will let you know which sites the traffic is coming from when a person signs up. It has other cool features as well.
What works for one may not work for others. It is ok not to try everything out there.
My two cents.