Hi Antti, I'm new here but I may have a few suggestions if you wan to try them. Have you thought about making an inspiration board of textures and objects that inspire you. There are lots of places to get poses of people from to help that aren't wear many clothes or use life drawing classes to amp up your visual library. Using references to draw from will help with your mental library as well as filling your sketchbook. Look at plants, animals, creatures from the sea or get your camera out and zoom in. Look at the shapes of the world around you to inspire too. And if you like films try recreating a scene that you have watched and change it up. another trick to help you would be using a character generator to give you a character description from clothing to where they are and their personality. I hope this was useful happy sketching.