If you are considering taking that huge step, check out the second edition of On Your Own! How to Start Your Own CPA Firm.
The first edition helped me a lot when I started my firm 10 years ago. It’s a great way to get your thinking started. It’ll point out a lot of things you need to address.
From the AICPA’s promo in the CPA Letter:
Now in its second edition and revised by author Brannon Poe, On Your Own! How to Start Your Own CPA Firm, leads new solo practitioners through each stage of creating your own firm, bringing your vision to reality and nurturing your practice to make that reality a success. Follow each of the book’s five parts as it takes you chronologically from start to success. Each chapter is rich with strategies as well as stimulating follow-up questions that will help you define your goals and plans, drawing you to careful consideration of important factors.
Also, I heartily recommend you read everything by Seth Godin, David Maister, and Ron Baker you can lay your hands on.