I require an engagement agreement prior to starting work. My firm's normal practice is to to do work on an hourly, fixed, and block rate (at a discount). The retainer policies differ by work terms. I typical submit clients with unpaid past due balances of more than 90 days to collections. I tend to make myself very available to clients, who can access me as needed. I like to work with clients who are responsive, fairly clear on what they want after I advise them of their options, and who are easy to work with.