I'm not an expert in art, but I goess I can help. I see that you're trying for the anime/manga look, so I'll start a bit
Head:
-They look like circles, generally the head is something like this :
-Also, their necks. They're big and thick, usually that means the character has a strong body (you'll probably see the thick neck being used on big-muscled guys most often) But from what I can tell, these are kids, not muscled beasts. Make them smaller plz
-Their eyes, they're too close together, they're supposed to be a bit more spaced out. *shot for hypocricy* Also, where are the eyebrows? You can keep those eyes if you want, but some people may have a problem with them.
-Their noses, where are they?
-The hair seems to mold to their skull. Hair does not do that. It is an uncontrollable beast that refuses to stay flat against our head. Just look at something like this:
^See where the skull ends?
Body:
-Tubes. Tubes everywhere. A human body is not tube-like (No matter how much we wish it were, thus drawing them becoming 1000x easier) There's more to it. I would reccomend the Upside-down triangle method to get you started.
-A girl's breast start from the armpit. Also, the breast aren't defined unless:
a)They're naked/wearing bra & panties
b)The clothes are tight
-Depending on the age of the guy, he usually has broader shoulders than the female.
-The clothes seem to be drawon onto the body. Generally clothes are slightly bigger than us unless they're skin-tight.
-Depending on the age of the girl, her hips should be wider. (Ex. Girls *age 18* usually have smaller hips than their mothers *age 35* but have wider hips than little girls *age 10*)
-The clothes are flat. Clothing actually has deph.
Legs:
I'm not even gonna go there, I fail at them too. But you still have the tube probelm as well as making them very small. Thighs are not small like that.
*shot repeatedly by a crowd of angry women*
