There are several must do's if you enter into a PCA with another professional or firm:

• you must be realistic!
• you must design an attractive compensation for your PCA partner
• you must realize you are trying to alleviate or eliminate the enormous amount of stress placed on your family and staff during a very difficult time
• you must acknowledge the PCA is a living agreement that needs to be completely reviewed semi-annually or annually
• you must consistently update the PCA practice procedures manual you will have created for your PCA partner
• you must consistently communicate to those surrounding you—staff, family, successor firm, etc.—the who, what, where, when and why
• you must acknowledge firms  that are passive with keeping their PCA Partners updated typically have poor results
• a good deal is a fair deal and all must be represented in the PCA itself---you, your staff, the successor or PCA partner and the clients.
• it must be acknowledged a PCA is not a succession plan it is a agreement that is designed to try and replace you immediately and there are many issues and challenges to doing so.  A succession plan is a scaled opportunity to realize the highest value, purchase price, client retention and growth of opportunity.  A PCA cannot provide much these benefits.

For your information:

If the Show Fits INSIGHT

Who Would Run Your Firm? Journal of Accountancy