There's an English TV show about a lawyer with one clerk and a receptionist. In each episode, there is one client needing help, with perhaps one or two mentioned as having issues (they'll be handled in the weeks to come). Things are always busy, but there's time for a cup of tea after the papers are filed away in the old cupboard. The clients, each one well known to the staff, are discussed over the cups of tea and it's all as cozy as all get out. These people never think of CRM solutions.
Customer relationship management is mostly about people. You need a way to store information, to make it available to the people who need it, and to associate it with the tasks it should be used for. This could certainly be done with pencil and paper and lots of meetings (or conversations over tea). If you have one client at a time and two prospects in the pipeline, that's a practical approach.