Summarize the background of the client or clients. Information such as where they are employed, their line of work or significant history like criminal records. In a financial case, details such as their credit history are important. Medical history is important to injury cases, and so on.
Sum up the facts of the client's case. Make sure to include details of the situation. For example, if a client is suing over a car accident, be sure to consider details from police reports in the memo. You will often be interviewing the client as well and not only reviewing documents of the case. The details the client provides could have a great effect on whether the firm offers him representation.
Include the action the client wants to the firm to take on his behalf. This is very important since lawyers are required do what the client asks, even if it would hurt the case or be against the best interest of the client. A lawyer provides advice but cannot go against the will of the client (unless it would require an illegal act).
Submit or forward the memo to your superior or whoever will be making the final decision on whether or not to accept the case.
Respond to the client with the firm's decision. A lawyer will respond with an offer or terms regarding payment or other requirements the client must meet before they will take the case.