Be specific with your guests. Send out invitation or reminder cards, and be specific about the duration of the party. Call the day before your party to make sure your guests are still able to attend. If you are having hors, make sure there is enough for everyone coming. A good suggestion is about two of each hors d oeuvres of each item for each person attending.
Variety is good, so don t just go with the regular cheese and crackers.
Think outside of the box. Try some different like puff pastries, Chinese egg rolls, or miniature Indian samosa's. Choose some hors d oeuvres that can be made and then refrigerated, this way you can make them days in advance. Do not serve all of your hors d'oeuvres at once. You want the food to last throughout your party, and not be gone in 15 minutes.