We know that solid wood planks were prominent from the turn of the century until balsa was introduced in 1926 by Lorrin Thurston. Heavily glassed foam boards appeared around 1948 and dominated until the change to shorter and lighter boards around 1970. You can narrow these broad windows by identifying the age of board specifics such as the type of cloth, fin style, coloring, stringer arrangement, shape details, etc. Generally speaking, the older a board is the more valuable. Most makers did not keep accurate or long range records on this matter.
Series generally add value to a board.
Carefully inspect any series logo for authenticity. Look for any sign of tampering, modification or after market insertion. The same advise regarding authenticity applies. The maker of a board can influence the value. This subjective call is a combination of clients' opinion and the makers place in the historical pecking order.