Ok, here's the first challenge of the OSHI art school.
You need to make a signature using good concepts of colours, depth, lightning, flow and blending. But you don't know anything about that, what do you do?! I'll tell here the link of a good tutorial, that teach all these things.
Also, that tutorial just help you to learn the composition of a signature, it doesn't say how to do it. If you have any question about how to do signatures, ask for xNill or Doxxy.
Good luck!