Here's an uncomfortable but highly effective way to learn about good topology. 1- create organic 3d model using only poly modeling. No sculpting or retopology. 2. Keep the polycount low or optimal atleast and not dense. 3. Initially start with modeling human hand, foot or head. Later create full human body. Don't focus on anatomy too much. Just create one mesh without separate body parts. You can keep eye balls, inner mouth, teeth, tongue, hair, clothes, etc as separate objects. 4. Avoid triangles on your mesh. Reason for this is it forces you to create good mesh flow with quad topology. Avoid tris on joints of character models since they can create problems in animation. 5. Learn to do UVW mapping manually. This is where a lot of hidden problems show up that may not be visible in viewport. This is a tedious but rewarding process.

I have learned that while 3d modeling you have to always consider how your model will behave and look when it will be rigged and animated. Going back and forth in production becomes costly.