Sketched with an empty stomach

I was so hungry when my mama was cooking, she made some Pizza I said to myself:go and do some sketches until the pizza become ready...

EDM challenge # 240

This is my first attempt of using oil colors

in fact this one is too bad, I know that, I am disappointed because I thought painting is an easy work, but now it seems to me that its very hard.
until now I do not know whats the problem but I need help and advices.
throughout the time that I spent on doing this, I liked mixing colors, thats very exciting