Cage cards
I started using cage cards for ID when I began raising rabbits. I had these awful metal holders and index cards. The metal holders got rusty and dirty and we all know what happens to the index cards. So I found plastic holders and plastic cards; they are readily available on line and at the rabbit shows. The plastic cards are used with an extra fine writing marker. Even if water of other liquid falls on them they do not smudge. They can be cleaned off with rubbing alcohol and used for a different rabbit. The cards come in many colors ...no surprise but I use pink for the does and blue for the bucks that are permanently in the herd. Young rabbits growing up have yellow cards for does and green cards for bucks. Once they are accepted as a permanent part of the herd they get their "grown up cards".Information on my cards includes ear number, color, sex, name, parents, and date of birth.
I understand some breeders will argue that they know their rabbits and don't need cage cards....well what happens if you are sick or out of town? The best thing about cell phones is that they let us be in touch 24 hours a day. The best thing about cage cards is that a care giver can tell you in one second what rabbit is the subject of their concern.
good management = good results