Fantastic advice, well said! Also Iffy I couldn't help notice that you are from Gosport - my family are from Portsmouth and most of them still live there! Everywhere from Fareham to Clanfield I moved away for University a few years ago so I'm not there anymore, but it was nice to see a familiar location!One thing I would disagree with is 'Want to make it the BEST!'
At your first attempt, I would do the best you can...let your friends in gently...don't try and make it too complicated...get them used to the idea of the Halloween party, then each year you can make it better. If you make it the best the first time, where do you go from there? Encourage them to join in with the 'spirit' of Halloween, help them with ideas for costumes, use examples from films, even non-traditional love stories maybe, such as between Igor and Dr Frankenstein!!