Finding a Vet
It is important to find a vet who is experienced in rabbit care. The best way, in my opinion, is through word of mouth. If you know someone with a rabbit, ask which vet they go to. Otherwise, ring around some local vets. Some vets offer free initial appointments, others free health checks with the nurse. The most important thing is to find a vet with whom you are comfortable.
Vaccinations
Rabbits should be vaccinated against two diseases - myxomatosis and viral haemorragic disease (VHD).
Myxomatosis is a fatal disease whereas VHD, although not always fatal, will make your rabbit very unwell. Pet rabbits do not need direct contact with wild rabbits to contact either of these viruses since biting flies and fleas can act as vectors. Vaccination therefore, is the only way to protect your pet rabbit.
They can start vaccinations from the age of 8 - 10 weeks, though this may vary at different veterinary practices. They will need boosters, which are either carried out yearly or six-monthly, depending again on the practice.
Neutering
It is recommended that, unless you are trying to breed, both male and female rabbits are neutered before they reach sexual maturity. The actual age that this should be done varies depending on veterinary practices.
Male rabbits
Most male rabbits are territorial and frequently spray urine. They will also have to live alone, which isn't fair on an animal that needs company. Neutered males are much happier and more relaxed. They can enjoy life without constantly looking for a mate and are less aggressive and smelly! Nearly all neutered males will stop spraying urine even if the operation is performed later in life.
Castration is a relatively minor operation which can be performed as soon as the testicles descend (10-12 weeks) although most vets wait until the rabbit is 4 or 5 months old, when the operation is easier to perform and the anaesthetic risk is reduced. The testicles are removed via the scrotum or lower abdomen.
Female rabbits
Having female rabbits (does) spayed is even more important. Most females become territorial and aggressive from sexual maturity onwards (4-6 months). They sometimes have repeated false pregnancies, and may growl at, scratch and bite their owners as well as attacking other rabbits. Keeping two females together - even if they are sisters - can make things worse. Spaying reduces and sometimes eliminates these behavioural problems.
Spayed females are likely to live longer then their unspayed sisters. Up to 80% of unspayed female rabbits develop uterine cancer by 5 years of age.
Spaying is a bigger operation than castration. It's usually performed when the rabbit is at least 4 or 5 months old. The uterus and both ovaries are removed via the abdomen.
Adapted from http://www.rabbitwelfare.co.uk/rwf/articles/neutleaf.htm