Family cookbook I'm in the (very) early stages of creating a family cookbook. Any tips you have on creating the book is welcome?

I did a project like that (my wife's grandmother's recipes) and ran into formatting problems when I formatted for letter paper, then tried to publish in folded (half sheet) letter paper. So base your aspect ratio on the 5.5" by 8.5" aspect ratio. This will eliminate a lot of white space in the vertical layout of the book.
Beyond that. Color "food ****" photos help sell a book, but can easily double the cost of publication.
Be aware of individual investment in recipes for family favorites. If several people submit the same recipe, list all of them as contributors, in alphabetical order.
Put casseroles in a separate section of the book, or in another book. Or not. I arranged my book alphabetically to show the influence of Campbell's soup on home kitchens. As an ingredient, this ingredient changed home cooking in the 1940s, not necessarily for the better.
Define the purpose of the book. I have a great cookbook that was put together to honor the memory of an outstanding pastry chef. Many are association fund raisers. If you use a publisher that works primarily in fund raising, copyright your book. Some publishers offer "best of" cookbooks from all of the books they have published.