Hips are fairly easy but can be difficult at first. Below
shows the differences between the female and male hips.
The female tends to be curvy and proportionate to the torso
while the male hip is rather straight and equal or smaller
than the upper body.
Let's take a closer look at the hip on the side view. Females
generally have a rounder posterior with males tending to
be less. The crotch area tends to protrude further than
the beginning of the leg and the waist differ for each gender.
The female waist goes inwards with the stomach curving outward.
Males has less of a curve inwards with a flatter stomach.
Of course, these are for slim people - this would change
if the person was fat or old.
Before we tackle the butt, lets take a quickie look on how
to draw the crotch. At the left most image, the female crotch
is drawn in a big "V" shape while the male crotch
is much wider and drops at the middle. Again, the female
is drawn rounded and the male is more angular. The same
can be applied to the backside - female butt is rounded,
male is more angular. There's a little trick to draw the
posterior. Females tend to have a rounded W shape that defines
their butt and males have a more of a stiff W bordering
on two U's beside each other.