The last thing you probably think you need to think about is how to thank the people who supported you through your enterprise of writing and publishing your book. Whatever the size of this magnificent stable of psuedo-fans–many of whom would also be in your cheering section should you, say, be on trial for murder–there will absolutely be important people you forget. Or people you should have forgotten. Friends may be slighted for reasons you cannot imagine, from their position in the supporter roster (“Did I make the first page?”) to their dissection of what names preceded theirs. (Clearly you, the writer, have a deficiency if that person supported you more than that one.)
Be aware of this possible disappointment, and don’t go off course because of it. Simply, it’s most important that you thank the people that must know that they contributed to your success. Be genuine. Then, no matter who grumbles, you know what you always knew: you thanked them for the right reasons.