Some things to consider when choosing a rabbit, such as boy or girl, what breed and how to pick a healthy rabbit...
Boy or girl?
This is of course a matter of personal preference but whatever sex of rabbit you choose you should get them neutered or spayed, particularly females who have a very high risk of uterine cancer if left unspayed. Neutering or spaying also makes the rabbit much happier and reduces destructive behaviour.
Male rabbits tend to be more easy going than females, are not so inclined to dig and neutering is less expensive than spaying.
Female rabbits can be more territorial than males and like to dig holes as this is their traditional role in the wild.
If you want two rabbits, the best pairing is neutered male and spayed female. The easiest, and often the cheapest, option is to adopt a pair of rabbits from a rescue centre.
Rabbits are classified into four sizes - dwarf, small/medium, large and giant. Larger breeds tend to be more laid back but have a shorter lifespan of 6 - 8 years, whereas small and dwarf breeds can live for up to 10 - 12 years. Obviously the size of your rabbit will dictate how much it eats and what size of cage or hutch you will need.
Long haired rabbits such as Angoras or Lionheads will need more grooming and Dwarf and Lop eared rabbits are more prone to eye and teeth problems which can be costly. Dwarf breeds also tend to be more highly strung and need careful handling.
The age of a rabbit significantly affects their behaviour. For example, rabbits often go through a "stroppy teenager" phase which can last until they are 1 or 2 years old. Older rabbits tend to be more laid back and sleep more. Rabbits sold in petshops are usually between 6 and 8 weeks old so if you think an older rabbit would be more suitable for you, try a rescue centre.
Whatever kind of rabbit you choose, carry out a basic healthcheck. The rabbit should be alert and interested in its surroundings. Check that the eyes are bright and clear of any discharge and that the ears are clean with no scabs or heavy build up of wax. The rabbit's bottom and feet should be clean with no caked on droppings and the skin and fur should be clean with no flaky bits.
Take your new rabbit to your vet as soon as possible for a thorough healthcheck. If your vet uncovers any health problems, don't be afraid to take the rabbit back to where you bought it from. Most petshops offer a one week guarantee on a rabbit's health and should be informed if the rabbits they are selling are poorly so they can take steps to improve welfare. Rescue centre rabbits will always have been vet checked before being put up for adoption but it is still a good idea to get your own vet to check the rabbit.