It looks fun, but in reality it takes a lot of practice. Why? Because the usual drawing practice of a figure or a face is to use a little wooden model or to attend live drawing classes if you can find and afford them. There is nothing wrong with either, apart from one thing: you draw what you see.
For example, I got tired of sketching cafe customers today, and decided to sketch a mannequin in a shop window instead... And pass it as a real beautiful woman in my sketch. Well, I did it. Mannequin didn't move, didn't go away, it was peaceful. However. When I finished it, I felt immediately that my beautiful woman looked lifeless in the sketch. Well.. It was lifeless.
A similar principle applies to live drawing classes. Sure, a person is real. That's good. But he or she sits for at least an hour under strict instructions not to move and not even to change the glance. As a result, you draw a stiff person bored, and it shows.
To make something looking convincing, you have to build some kind of rapport with your model. Long time ago, in art school, my teacher used to say that to make a good still life, you need to be hungry. Then you want to eat what you draw.