First, pick a breed. You can narrow it down to a couple breeds and see what is available in your area.
Next, do some research into the standard of the breed. You can buy the Standard of Perfection for ARBA or see if you can borrow one for someone. While you might not understand everything at once, you can look at the DQ's and what that breed should look like.
Find a good breeder. You can check show results to see how their rabbits do at shows, but also ask other breeders. If they have pictures on their website, try comparing those to the standard.
Shows can also be good places to find breeders and rabbits. You can see for yourself how the rabbits do and compare rabbits from different breeders.
When contacting a breeder, tell them what you are looking for. Be specific as far as age and colour you are looking for. you might want an older rabbit (not a baby) as you can get a better idea of how they develop.
Keep in mind that a good show quality rabbit will be more expensive and most breeders will not sell their best stuff. You really need to breed to get your own really good show rabbits rather than buy them.
It is important to know what you want. It can be overwhelming at a show or going to a breeder and you need to be objective. Look at each rabbit and take your time.