The design looks professional-enough to me. Better than a lot of B2B sites that make a killing. The logo is the weakest link design-wise. The V symbol is alright, but the fonts are poorly chosen, the color and edges show compression, the edges of some of the type is blurry, etc. You might want to give your call to action buttons (Start free trial) a color that stands out, maybe a bit bigger. The idea is to make it clear to the user what their next step is. Also, why are there two call to action buttons, sign up and start free trial, when they basically mean the same thing? I'd maybe suggest having a big sign up button with "30 day free trial" in text below, or something to that effect.
The copy is a bit clumsy. Definitely have a native speaker with some linguistic savvy look it over.
In terms of getting clients though nothing mentioned above may be a factor. What is your conversion rate? Improving your site will improve on that, but if no one is coming to your site then marketing your site is a more important step to address.
Do you have any existing clients? How has their feedback been?
I'd recommend finding people for whom you've delivered well and investigating what worked well about that relationship. Maybe they can give you referrals, maybe you can target people in similar situations, and so on.