Spooky parties are mostly social interactions. The one thing that you need to be mindful of is that pumpkin carving, because it takes a long time. One thing I did notice is one of your sims can ask a guest sim to carve a pumpkin, so if you only have one sim in your household you can have them draft a guest to do your pumpkin carving while your sim does all the needed socializations. Just make sure to keep an eye on them, so the carving gets done!