Often with me i draw from 电影院 sometimes and it helps me think a bit and helps me work through challenges. 你 could also give a comic strip a try. Like the person before me 说 take a scene 或者 chapter from a book 或者 your own mind and draw a little comic strip for it.
From my view of your drawings I've got a little constructive criticism for you. 你 lack dimensions. That is something 你 could work on trying to make drawings with perspective and add shadows. A good exercise to work on it is exploding box effect. At this link 你 can see a pretty good example of it.
link Another thing 你 could do i learned this from my art student teacher. 你 put dots down in a pattern with curves like 你 can make a cursive l 或者 C etc. 或者 something 你 designed yourself as many dots as 你 want my first one was about 200 something anyways. Your total number has to be a multiple of three. When 你 divide your number 由 three it should come out without a decimal. Once 你 have the number 你 go to the dot number that it is and start drawing lines from there each dot should have a dot corresponding to it. 你 draw a line from that dot number to number 1 and then 你 go to the 下一个 one and draw it to two and so on. I believe it was called a helix when it was explained. It should look like a cool spiral type thing when its finished