Halloween face painting idea 1: pumpkin
A   bright orange pumpkin painted on each cheek.  Black paint used to paint   eyes, nose and mouth. A light grey would be  used to show the ridges of   the pumpkin as well as its outline.
An  alternative would be to do a   full face pumpkin with an orange face base  (blending a darker orange   shade over cheekbones), black triangle shape  over the eyes (extending   above and below the eye area), a black nose and  a large black mouth   (need to cover more than just the lips).
Halloween face painting idea 2: skull
A   full face design. Has a white face as the base,  large black 'panda'   eyes, black and white vertical stripes on the lips  (with the white   stripes wider than the black ones) and a trickle of red  from one side   of the mouth (to indicate blood).
Halloween face painting idea 3: vampire
A full   face design. A white face base, bright red  lips, fangs coming out of   each corner of the lower lip (outline is light  grey, fill is white,  and  tip is red to denote some blood), eye lids are  smoky grey (right  up to  and over eye brows), eye brow then exaggerated  with black  sweeping  strokes.
Halloween face painting idea 4: bat
A   full face design. A white face base, bat's face  painted on forehead   above the nose (it's in black with light grey for  eyeballs, and for   some definition in ears); the bat's body is painted in  black on the   nose and ends at the base of the nostrils (use different  shadings of   black; the bat's wings extends out from head and body and  covers the   eyes curving up towards the temple and down the outside of  the eye to   mid cheek (again use different black shadings and some fine  dark grey   strokes to paint some definition into the wings); the lips are  painted   in dark grey with an exaggerated upward curl at the corners.