I've started using different acquisition channels to get my first customers. And it worked! I've got more first 10 customers, totalling $340 in order value!
So happy to see real-customers creating real paintings. Most customers come from US and NL. But i've also seen my first customer from the UK.
A positive sign is that 2 of these customers ordered 2 paintings at once. So it seems that I have to build a shopping-cart feature soon. Oh no! ;-)