I'll admit I don't know anything about this topic. I'm only blogging on it so I can maybe collect some ideas.
My third novel will launch in just a few weeks and I have nothing planned. I didn't do book launches for my first two and am not sure I'll do one for this one.
From what I've observed, one serves at least wine and cheese, and maybe has giveaways for all attendees. That sounds like one will be spending money one has not earned yet. In my case, it may be more money than I'll earn from the book in quite a while.
Then there's the venue. Where does one hold a book launch? Ideally, the launches for the Imogene Duckworthy books would be in the Wichita Falls area. To be sure, I lived there when I started writing them. But I don't now! I'm a good two hundred miles away, over three hours on the road, and I'm a terrible long-distance driver.
Here's what I do: I try to guest blog a lot just before and around the time that my book is coming out. I give away books on some blogs. Now that I have more than one out, I'm giving away #1 and #2 in prep for #3. I schedule signings. I give talks and appear in person whenever and wherever I can. There are writers' groups, book clubs, library events. I attend conferences, but can only afford the time and money to attend a few at this point.
I hope it's enough!