The best book clubs are group efforts rather than dictated by one person. So if you want to start a club, put it out there and wait to see who is interested. At this point, it's good to be honest about what you like to read. So in the Facebook post where you announce your plan to start a club, you might mention one or two books you like. That will weed out those who don't have similar tastes.
Once you have some interest, set a date to meet to discuss how the club will work. Remind everyone to bring their calendars. At that first meeting, allow time for introductions and maybe each person can name a great book they love. Once everyone is comfortable, it's good to go over the "format" of the book club. These are not your rules, these are suggested by other book clubbers. Then, given the suggested format, talk about what you each want in a club. Remember that you can change the format at any time if you all decide that you'd like to try something else.
In early meetings, it's good to go around the circle so one or two people don't dominate and everyone feels included. You might have everyone name one thing they really liked about the book. You can keep that format for the book discussions for the first round as well if you feel that helps everyone participate better.
At this first meeting, you're also deciding when to meet, how often (most clubs are monthly but you can do what works for you), and where you will meet. The hardest part is how to decide what book to read. You'll need to leave time at the end of every meeting to pick a book (usually you're picking two months ahead). Most book clubs end when people stop reading the books because they don't like them. Nobody wants that. A great way to pick a book is to have each person take a month and present three books (rather than one) to the group as possible options. Then the group votes on which of the three it will be.
Add food, add wine, and you've got yourself a book club!