Tried different prices for premium accounts. Increased difference between paid and not paid accounts visibility on site. Started approaching different business that could be interested in ads directly. Started reinvesting earned to actually market the site.
Marketing was interesting. I contacted around 10 of the best artists on site and proposed to manage the AdWords campaign for free and pay 30% of it from my pocket. In return, the target would be not their own site, but the page on arts.in.ua.
3 people agreed and we end up spending a combined ±700$ on that.
There were some results but not much so I consider it a failed experiment.