Hey /ic/, how do you politely tell a friend that their art sucks and they really need to study basic art theory?

I have a friend at uni who wants to be a proartist, but he's absolutely oblivious to the quality of his art. He draws really crappy stylized "people", and when he does studies he does the proportions stylized as well (the heads are realistically drawn, but huge compared to the body like in anime crap)
The teachers just give him asspats in his entry-level drawing class, but I know he's going to get ripped to shreds when he gets to higher level classes.

He's a really nice kid who's just going in the wrong direction, and I don't want to see him crash and burn. Everyone can improve with studying, but I don't know how to tell him how bad he needs to do studies.

I am but a simple hobby drawfag pursuing a major in science, so I also feel like he wouldn't want to listen to me. What's a nice way to do this and not make him feel like I'm being pushy or rude?