Often with me i draw from cine sometimes and it helps me think a bit and helps me work through challenges. tu could also give a comic strip a try. Like the person before me dicho take a scene o chapter from a book o 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. tu lack dimensions. That is something tu 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 tu can see a pretty good example of it.
link Another thing tu could do i learned this from my art student teacher. tu put dots down in a pattern with curves like tu can make a cursive l o C etc. o something tu designed yourself as many dots as tu want my first one was about 200 something anyways. Your total number has to be a multiple of three. When tu divide your number por three it should come out without a decimal. Once tu have the number tu go to the dot number that it is and start drawing lines from there each dot should have a dot corresponding to it. tu draw a line from that dot number to number 1 and then tu go to the siguiente 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