when i bred all my tattoos fallowed these lines:
K (always first, for "Katt's" as my rabbitry was Katt's Rabbitry) then the year number (for the # of years i was in rabbits, like my last litter had a 5 as it was my 5th year of breeding), the litter letter (restarted this at the new year, and each breed had its own abc's), then the kit number (even for girls, odd for boys)
so i might have a kit called "Katt's K347"
so, that kit would have been born in my 3rd year of breeding, from my 4th litter of that year for the breed and would have been kit number 7. . .it took me a while to get a good system, but it worked for me and the number of litters i tattooed.
also, i tattooed "PET" in rabbits that either by appearance or genetically i didn't want to sell as breeding or show stock, that way when people came out to buy rabbits all i would have to say is that "PET" tattoos mean no pedigrees and not show/brood quality.
basically, you find your own system and go with it