the right and left arm seems out of proportion.
seriously for FIRST time, its still ok la..not bad d..just do more research on human body proportion and practice in a correct way..proportion is always the biggest problem that normal ppl will face. even include me..still will have some proportion probs..esp the 2nd and 3rd one, its either the head too big  or ur body too short..

so good luck! =) post more of ur drawings here in future! 
hey did u refer to ur own hand before u start drawing? coz according to the ur palm shape direction, most probably ur thumb wil not be like this isnt it?  correct me if im wrong. im not really sure though.

get reference book. 
or sometimes you try post your work and see who is free and hand itchy to fix your work then you know what things you are lack of.