First, I hope bookkeeping is not in your position description. Yes, you need to know the basics of the bookkeeping function, and your CPA is a good source for a quick overview of what is involved. But I want you to practice law, not do the bookkeeping. I think I just heard a roar of agreement!
How to find a bookkeeper familiar with law firms? Your state or local bar association may offer a practice management service. The person performing this service is known as a practice management advisor or PMA. Ask whether they have a list of bookkeepers familiar with law practices, particularly the trust accounting part. If not, a web search or asking other attorneys will turn up some names. I think a bookkeeper’s personality is a factor for whom to choose. A bookkeeper’s personality should be open, pleasant and not defensive or secretive. This means a bookkeeper will be willing to explain and share information in a helpful fashion at any time. But again, knowledge of the law firm trust account rules is essential. In Washington, the state bar offers an excellent booklet describing the trust account rules and bookkeeping methods with illustrated examples. So, check for this resource with your own state bar association. Another good but little-known resource for financial information is the IRS Attorneys Audit Technique Guide.