A Halloween party is probably one of the easiest parties to have. The decoration choices are countless and trick-or-treating takes up much of the entertainment, so your main concern may be creative Halloween dishes.
A very cute idea for serving popcorn: Put a piece of candy corn in each tip of a clear plastic (non-powdered) glove to be the fingernails, and then stuff the glove full of popcorn. Tie the end shut with a Halloween ribbon.
Spooky ice cubes: Add toy spiders, bugs, etc. to your ice cube trays along with the water, and then freeze. Add these spooky ice cubes to drinks. Be sure to choose plastic spiders and bugs that are large enough to not be swallowed once the ice melts. Wash these spooky trinkets well before use.
Orange round crackers can be used in many ways for decorative snacks: add peanut butter and raisin eyes, nose and mouth (or use mini-chocolate morsels) for a jack-o-lantern look. Add stick pretzels as legs for a spider treat.
Choose orange or black colored chips and pre-made desserts that have the Halloween colors. This will be less work for you, but add to the ambiance of your theme.
Research your choices and be creative. Your Halloween party will be a great success!