Well so far I didn't take draw lessons , mostly I tried to see what others draw and try to remember every single details on that sort of subject , and later when I have studied a lot more clearer I try think and see what my mind/brain can come up too and convert that on the paper {draw it on the paper}.
It's pretty nice to draw what your mind/brain tells you , like you just think of something and try to decrypt it on a paper. {Its like converting a illusion to reality}