Try spending a little more time on your pieces. This may be beginner, but 6 minutes isnt a lot. Use the tools to their fullest and try more consistant colouring.
I agree with cianteed... Try to choose a wider canvas than you need in order to have space for better proportions... I find this picture to be quite squished... Also, try doing the colors in different layers so as to prevent overlap or spaces where there is no color... With more solid colors, it is easier to shade your work... I find that this has no definition or depth to it... please try harder next time!
drawn in 6 min
drawn in 33 min
drawn in 9 min