And I think … it looks like a simple character model, but I don’t know how to start trying to draw something like that.
For example, the boots, any idea about how they should be drawn? or any tutorial / video that can show me how things like that are modeling?
As with modeling anything, the first questions is, do you have a firm grasp of the basics?
I fully believe that something like this can be created in Sketchup, but you will need to know the basics of modeling and then learn to take advantage of a few extensions. I would probably use a lot of Curviloft in this model, as well as Vertex Tools and SubD for the face and body.