I started out with a convoluted system that that had abbreviations for film size (sf, mf, lf) followed by type (similar to roteague) and then incremented them.
I abandoned that system (I shoot way to much to have to stop and think) and simply put the negs in sleeves with a contact (digital or traditional), tranies do not get contacts, number the contact and the sleeve and put them in order in loose leaf binders.
The simplicity of the system made sure that it was done. I will in the future go through the binders and reorganize them by subject and renumber within the subject and add a subject prefix.
Commercial work is by client then job.