Often the inclination is to add in more and more criteria, not considering how they are linked with the actual research objectives, and not considering how they are linked with each other. Consequently the identification of the weights is passed over very quickly, or is completely forgotten. Scoring methods may become shouting exercises, where the obvious problems of the loudest voice get priority. They have then become too ad-hoc, and are being used to escape from a more substantial effort to collect data and focus the mind. Scoring methods are among the most basic decision support tools.
Software is available from many different sources.
In addition, there are many textbooks on decision making, that will provide a basic introduction to scoring methods.