[First off, set up your party page. This is as easy as creating an event on Facebook. **MAKE SURE YOU SET YOUR EVENT TO "PUBLIC" UNLESS YOU REALLY WANT GUESTS TO BE INVITE-ONLY. Here's the link to our Summer Release Party Page.]
1. Team up with other authors. This takes the pressure and time commitment off you. Even if you're hosting your own release party, invite other authors to host/take over for 1/2 hour or hour-long slots, to give you a break (and to offer your guests some variety).
2. Set a specific time frame (and consider keeping it short!). Our party last week only lasted 3 hours. Since there are 6 of us, we each took 1/2-hour slots to host. This seemed like plenty of time, and those who couldn't attend during those 3 hours could still stop in and catch up with the posts on their own time.
3. Post on your party page ahead of time. This is fun: post little teasers for your guests to get them excited about the event. We shared pictures of our prizes, our virtual hot guy dates, our virtual party gowns...you can be as silly or creative as you want. Get people talking!
4. Plan your posts/giveaways ahead of time. I always do this just so I don't have to fly by the seat of my pants when I'm hosting. I have 5 or 6 posts already written out, in a Word document, and then I just copy and paste onto the party page
5. Include pictures. This is always fun and generates discussion. Ask your readers to post pictures too! I'm a fan of hot guy pictures, but in our last party, hosts posted pictures of favorite Southern dishes, favorite small town locations, wedding gowns (good, bad, and disastrous)... The sky's the limit!
6. Interact as much as possible. If you have a lot of guests actively posting, it can be hard to keep up, but do try to respond to everyone who comments on your threads. Readers love to know they're talking to authors and interacting on a friendly, personal level.
7. Have fun giveaways and prizes (and follow up with announcing the winners!). Readers attend release parties to win prizes, no doubt about it. These prizes don't have to break the bank, by the way; I've given away $5 Amazon gift cards and I've seen people give away Kindle Paperwhites. It's all what's within your budget. But make sure to have your readers do something notable to be entered! I usually ask them to comment on a post, sign up for my newsletter, or follow me on social media. Warning: you cannot legally require anyone to make a purchase to be entered into a giveaway, so don't ask someone to buy your book, or anything along those lines. Also important: make sure to award those prizes! Announce a time when you'll be selecting winners, and follow up with that. I usually go back the next day and post a separate winners announcement on the party page, along with an announcement on each "giveaway" post as well.
8. Have a separate thread open for discussion among hosts. This works well especially in the case of glitches. I've always had an open Message thread running on Facebook while hosting a party, and this allows the hosts to comment on anything that's happening, remind each other who's up next, ask for help in the event of technical difficulties, etc.
Above all, have fun! The more you engage with your partiers, the more fun everyone will have (and the more books you'll sell!). Good luck!