Well if you want it to look painted, then it’s a lot of texture painting. In which case you can learn to texture paint. So maybe the old axe painting can do:
https://cgcookie.com/lessons/texture-painting-a-low-poly-ax-pt-1
Or if you want to go geometry, then maybe with the things learned in Cubicity or Stylized forest:
https://cgcookie.com/courses/cubicity-creating-and-utilizing-asset-libraries-with-blender
https://cgcookie.com/courses/creating-a-stylized-3d-forest-environment-with-blender-2-9
