Start by drawing
a general sketch, or a "skeleton". The ratio of the body must be correct for
a natural feel. These are the tips:
-Elbows at or above the waist line.
-Hands at hip or middle of thigh.
-Body length (from shoulder to hip) is about the same as length of
legs.
-Head shouldn't be bigger than the waist line for adults.
(unless you're drawing children or cute characters)
-Draw the spine (lightly) as a reference line.
-Leave a space between the legs below the hip.
-Make your characters lean slightly backward for a dynamic feel.
DIY: Look at yourself in the mirror.
Head:
When
starting on heads, most manga tutorials draw a sphere first and then
continue with the chin, with the result like this: (from
www.howtodrawmanga.com)

However, I prefer to just draw out the whole face in a few strokes, so there won't be a lot of construction lines to erase. The result would be something like this:
Eyes:
The eyes are the window to our souls. This goes
the same for manga/anime characters. Eyes are important in giving your
character life and emotions. To start, position the eyes around the middle
of the face. To draw the eyes...(Sorry, I don't know how to instruct
properly, just have a look at the examples and copy them).



*Remember to curve according to the face.
Shading:
There are many ways to shade the inner eye, just keep experimenting
until you get the one you like. Here are some of my favourites:

Expressions are mostly conveyed through eyes, these are but a few examples:

DIY: Refer to your favourite manga
Nose:
......Just draw a few lines, or none at all. (I
don't think its worth showing examples of noses).
Mouth:
I don't usually pay a lot of attention to the
mouth. Here are a few examples:

Ears:
Ears are very hard to draw (for me). I can't seem
to get a nice looking pattern. Just have to keep referring and practicing.

Hair:
There are many, many types of hairstyle that could be found in manga/animes.
With so many already drawn, it's hard to cook up an original hairstyle. One
important rule is to draw the hairs in a single stroke, or else it would
look funny. This is hard when drawing long hairs. Here are some samples from
the endless sea of choices:

DIY:
Refer to your favourite manga/anime and take note of the hairstyles of
people around you.
End Note:
Wow! Just doing for the head and face already took so long. Can't
imagine how long it would be giving tips about drawing the whole thing.
Sorry folks, this is as far as the tips go. Got to focus on my studies. I
may update this section when I have the time but I most probably would be
too busy (or lazy) to finish it.