It all depends on your imagination.

If you decide to apply the plaster manually, then the layer must be done not too thick and not too thin. That is, choose a certain «golden mean». After the full application of the solution on the entire surface, you must wait 30 minutes. This time will be enough for the coating to «grasp». Next, pick up a plastic grater and begin to make drawings. For example, you can create «circles» or «direct rain». It all depends on your imagination. At the same time, remember: when making the drawings, make sure that the surface of the walls is even.