This is how I do it.

The year born along with the sex of the animal. Then it's morph name. Then it's individual number.

Here's some of my animals numbers..

03F-NORM-01
10F-PSTL-01
10F-PIED-01

For a het, I just do something like this...

10F-LSSRPHH-01 (Lesser Possible Het Hypo)
03F-PHCA-01 (Normal Possible Het Caramal Albino)

etc...