Although I have filed suit against delinquent clients...the number has been relatively small. Usually serving them with a summons is enough to obtain payment. In the majority of cases simply sending them a summons by certified mail return receipt requested with a letter indicating that suit will be filed was enough.  There is a difference between filing suit and serving a summons. Even if it is necessary to serve a summons by a sheriff, it is less expensive that filing the suit, and the delinquent client gets the message.

Care needs to be taken to observe the civil procedure of the forum state. In some states it is necessary to file suit first,  and serve it afterward. In Connecticut the reverse is true.  It will also depend upon the business form that is chosen by the Plaintiff. In most states a corporation and LLC can not be represented in litigation by their officers/directors/members unless they are also attorneys because it is an unauthorized practice of law. However, in many states an exception is made for small claims suits, and the state's position on this matter will probably be explained in a brochure available to the public.  Small claims summonses can usually be obtained off the internet or through the mail.