The most important aspect of breeding is keeping accurate dates to when these animals were bred, and when they are due. I recomend keeping a calender in the barn, write down both parents, and the date bred, if you are unsure if they took write in down anyway, better safe than sorry. While you are recording this mating, flip to the due date and mark it on the calendar as well, so you are sure not to forget. This is important to the young as well as the mother.
Also keep all pedigrees of the animals that have them, when they reproduce make pedigrees for the young. This is responsible breeding, that way future breeders know if animals are related and a general genetic background of the rabbit.
Other records that are important to your rabbitry is accounting records and show records. This allows you to know your money boundries, and what your animals lack on the show table.
I personally use a computer program. This software maintains my pedigrees, matings, accounting records, and show records. This allows me to know everything that has happened with my rabbits and all future plans. It is additional expences however is worth it.
When caring and breeding rabbits you must be prepared for everyting, if you are going to make the decision to reproduce animals you must be organized and give each one a chance at life, and ensure that the reason you lost rabbits was not due to your neglect and ignorance of rabbitry managment.