It really is hard to find some useful tuts to draw people.
I don't really like Manga. Good you want to try 'real' people.
I've got nothing against manga if it's professionally done (although it's not the style I like looking at). But it's rather annoying, that everybody who's too lazy to draw real persons, draws manga. It's really annoying
Everywhere on the desks in school there are those manga figures. Just because there are a pair of standart eyes, standart noses, standart mouthes.. the strange expressions.. Terrible.. (hope I didn't offend anyone.. If someone really likes manga, he, or she, could tell me what they like about it and try to convince me).
But the best thing to learn drawing people is to draw anyone who stands still for a while ^^
But of course you could watch your reflection in the mirror and try to analize the different bodyparts in their relation and so on. Or get a Barbie and draw an easy sketch just consisting of geometric forms.
But I'm afraid you have to practice a lot. And the perfect shape of people jsut comes with the huge amount of attempts. But I'm afraid I lost the websites of some good tuts... (*going to google*)