Identify the appropriate matrix to use. In approximate order of common use, these are:
The L-matrix is by far the most common diagram. If there are more than two lists, then a set of L-matrices may still be the best approach, unless the additional relationship mapping given by other matrices is required.
The T-matrix is useful when there are two distinct sets of questions about a core list, for example comparing school subjects against students and against teachers. An indirect relationship can be inferred between the two side lists.
The Y-matrix closes the loop on the T-matrix, and is useful for comparing three tightly coupled lists. It can also be used as a practical simplification of the C-matrix.
The X-matrix is useful for comparing two pairs of complementary lists, with each pair occupying diagonally opposite lists (as they have nothing in common and need not be compared). For example comparing men and women against activities in athletic and intellectual pastimes, with men and women opposite.
The C-matrix compares three lists simultaneously, such as the people, products and processes in a factory. Being three-dimensional, it is difficult and complex to produce and draw. It becomes easier if there are few relationships to map.