Looks like you haven't written a new blog post since May 4th.
Looking at your source I have no idea what your most important keywords are, I think you really need to understand the key-phrases which people use to describe the kind of product you have made -- and then you need to optimize for them. 'Multiple revisions'? I think theres gotta be a better search phrase describing this product. Maybe 'mockup tool' or 'revision tool' (note: havent done google keyword search, just off top of head)
Are you actively engaging press? You need to write up a reviewers guide and ship it off to every tech writer with a decent designer audience that you can find. You need to personally email every author or blogger who says something good or bad about your competitors, are you doing this?
Do you comment on high-trafficked freelancer/designer blogs? Do you participate in freelancer/designer forums?
Are you collecting emails anywhere? Preferably on front page! Use MailChimp it's free for less than 1,000 subscribers. I would be far more likely to give you my email address then to signup. Once you have me on your email list you can have a time-based email campaign that introduces people to your program and offers discounts towards end of trial period.
Just my .02