Just use MS Paint and keep at it
Zoom in at 800%, press CTRL+G to activate the grid when you need it, press CTRL+F to get a quick look at your work zoomed out, and any key to go back to normal
Use the Pencil tool for most things, if you need to make things look symmetrical, copy/paste and then right click and Flip/Rotate -> Flip Horizontal/vertical
Keep drawing and colouring people from various angles, it wont be long till you notice yourself improving
Zoom in at 800%, press CTRL+G to activate the grid when you need it, press CTRL+F to get a quick look at your work zoomed out, and any key to go back to normal
Use the Pencil tool for most things, if you need to make things look symmetrical, copy/paste and then right click and Flip/Rotate -> Flip Horizontal/vertical
Keep drawing and colouring people from various angles, it wont be long till you notice yourself improving