avoid making the chin pointed , make it a little rounded. your every character u made they look as if they are going to play NEGATIVE ROLE IN MANGA. HAIRS make it a little bit loose not so hard spiky. AVOID long necks.
for the SIDE FACES you are making the nose too long avoid that.
well if it is your first time its ok .
PRACTICE LOTS OF FANARTS THEN JUMP TO TUTORIALS FOR BETTER UNDERSTANDING..
i guess that will be enough for you to improve.. I USE TO DO LIKE THAT BEFORE.. HEHEHEHEHEHEHE