Here's a great book to help you plan your Open Studio:
Open Your Studio: Nine Steps to a Successful Art Event by Melinda Cootsona
This inexpensive book is full of really good, solid advice, including tips on pricing your work, choosing what to display, framing, presentation, attracting customers and more. Melinda has done a lot of very successful open studios and shares her experience with what works and what doesn't work. Some of her tips may surprise you, so the book is well worth consulting, especially if you're doing Open Studios for the first time.