Promote For Free, or Push For Premium?

Hey WA,
Today, I want to pose a question to the community, and see how many different answers I can get, as well as see how many of you go about this.
I want to talk about promoting WA, and how does those who are promoting WA go about it.
I am not talking about traffic strategies or anything like that. I am talking about when promoting it, do we offer it for free, or promote the premium sign-up right off the bat.
I was always under the impression, that it is good to promote it for free, this way they can get a taste of it and always upgrade.
I was also told that if they were serious when signing up that they would most likely upgrade anyway.
The reason I bring this up, is that I have had a month where I got the most referrals I have ever received, but not 1 went premium.
I was wondering if maybe I should just promote the premium membership, and for the discounted price, that more people would go premium from the start.
I am just curious as to how others have gone about this. There is nothing wrong with a Free offer, but people buy things from the start all the time also.
I have also been told it's just a numbers game, and to get the most free referrals as you could, and eventually the premiums will start to trickle in.
I am still promoting it for a free start, but I was curious about other more up front strategies about asking what I want from the beginning.
I may do some split testing, but I am very interested how the community feels about this topic, and how they have gone about this approach.
Thank You WA,
Chris
All the best
Darren :)