What types of businesses or people are your clients?
Look for an accountant who understands and has worked with people in situations similar to yours. There are ins and outs to every business, from understanding how and whether to hire contractors or employees in the construction industry to managing the legal requirements of escrow accounts in the real estate biz. An accountant who has experience in your industry can make you aware of potential pitfalls, pain points and deductions.
Similarly, if you're just starting out, you may not have a whole lot of money. That means an accountant who works with millionaires probably won't even answer your calls. Fortunately, you probably don't want that accountant anyway. You want the one who helped get those folks to the top, not the one who gets paid a lot of money to keep them there. Talk to friends and business colleagues in situations similar to yours and find an accountant who understands where you are now and where you want to go.