It really depends.
Sadly, my parents aren't really the type that celebrate holidays. (Except for Christmas, New Years, Thanksgiving and Easter. Although most families have other family members come over during Christmas, Easter, Thanksgiving etc, we don't.)
Last year it POURED during Halloween (though some people still went though they were soaking wet and caught colds), the year before that I passed out candy (the kids were so cute), the year before THAT, I was... a ballerina (don't ask) and the year before THAT, I was... Jigglypuff. =___=
So this year I'll probably just pass out candy, spend the night over at a friend's house watching horror movies or go trick-or-treating... I guess I'll go as a female ghost from an Asian ghost movie. .__.