Here is a growth hack for you, Put $100 towards AdWords and bid cheap(shoot for less than a quarter per click) and send users to a free trial landing page. Little tweaks here and there obviously help, but at some point you just need more traffic.
I will give this a try (along with other ad networks as well) when I've got the conversion rates to a better level.
How do you know visits from ads won't convert any better than your current visitors? If you do a half-descent job of targeting your ads you could get visitors who are much more likely to convert than your current visitors.