Axel, a key element in any drawing is proportions. Now, when making the head (especially for anime manga type stuff) always start with as perfect a circle as you can. You'll then add the chin line, wich will vary in sive depending on the angle of the characters head. Then, according to the size youve made the head, you will want tomake the shoulders about the width of two of the heads youve drawn side by side. This outline will keep the upper body and torso around the right size and give your character a tad bit more dimension. for the face, it really comes down to having an artistic eye, but if you want correct placement for the eyes nose and mouth, reffernce lines are great tools. You will start by drawing a straight line, directly halving the head, and this will set you up for having facial symmetry, wich is crucial if she or he is not going to look deformed. Then add the eyes about half way up on the head (depending on the angle) the mouth should be no wider than the width of the eyes, but in the case of manga or anime type stuff that may be entirely too large.
I hope this helps but just remember i started drawing this kind of art like 5 days ago >.<
Ill be sure to put up some of my art (thats not in need of censoring) To show you how i like to do it.