Section 12. In each city, and in each town not included in a district established under section ten, and in each such district, there may be in the department of veterans’ services an unpaid advisory board to be appointed, in cities by the mayor, in towns by the board of selectmen, and in districts by the district board. Said advisory board shall render such assistance to the director of veterans’ services of the municipality or district relative to the provisions of this chapter, except as to sections one to nine, inclusive, as said director may request. The commissioner is hereby authorized and directed to formulate and publish rules and regulations establishing in a general manner the types of persons, with respect to their occupations, professions and special skills, who may be appointed to such unpaid advisory boards. Every such advisory board shall consist of not less than five nor more than fifteen residents of the city, town or district, as the case may be.