Halloween is a human holiday occurring on the thirty-first of October (an Earth calendar date). The origins are dubious in nature but the traditions include children dressing up as something frightening, iconic, cute, or of future ambitions (such as a c-sec officer or royalty [yes we know this isn’t a reasonable occupation. Children enjoy the idea none the less.])
While dressed up, these children will walk from door-to-door at night (or earlier depending on how young the child is) asking “Trick-or-Treat”. Traditionally, this is followed by the inhabitants to hand over a few pieces of candy. If you do not have any candy, I advise you do not open your door to them as it’s terribly depressing for the children. If that is not reason, “Trick-or-Treat” is a bit of a threat of mischief to be brought if no treat is given. This is mostly hollow but the keyword is mostly.
Adults will also dress up (although usually in more sexually charged outfits), but this is mostly for costume parties rather than “Trick-or-Treating”. Parties are usually normal except perhaps with more sweets and decorations. Some of the (better) parties will also include watching various horror films.
Since Halloween has spookier roots, decorations come in an array of horrifying; Arachnid webs, skeletons, undead, etc. Most iconic is probably the Pumpkin. A large orange gourd-like squash whose guts are emptied and flesh cut into scary faces or other designs. Then a candle, or other small light sources with particularly long lifespan, are placed in the middle of to accentuate these designs. (I advise if you decide to carve a pumpkin that you do not do anything particularly ambitious as delinquents enjoy smashing them while no one is looking.) Orange and Black are also considered the holiday’s official colors.
Most decorations aim to be spooky but also light-hearted (as it is primarily an event for children.) There are those who go more for the pure terror aspect. For these (and by these) people, there are several attractions that spring up. “Haunted Houses” and other such places are completely renovated with the scariest decorations and several “actors” (many of whom I can guarantee haven’t acted before in their life) whom serve to scare those who pay for entrance.
If you do want to hand out treats to children, it would be wise to decorate the front of your door to make your hovel more identifiable for children. I would also avoid reanimated dead, as the Reaper War has made such things a bit of a sensitive topic.