Well there, Snails, I've seen your very first 10 minute sketch of a face. I must completely and totally say, that your potential is definitely on the right track.
And as for a tiny bit of aid, it would be to say that your face is a little bit scribbly for my tastes, yet it needs to be more loose and bolder. Why don't you please go for 10 minutes of 5 minute faces and expressions????????? (10/5=2 drawings of expressions)
The reason why you would be trying and be going to do this is because, your faces will slowly become the least stiff, and gradually become more fluid, vital, and lively, but your myelin will thank your for this special task for you. If you really need more unique info, be sure to look up a PDF, or an out-of-print book, of Nick Meglin's Drawing from Within. (Mad Magazine)
Good luck from me, and I hope you've found this definitely and absolutely useful and encouraging.