The best way to find a good home for a bunny is to advertise in veterinarian's offices, pet stores and other places that might attract people interested in a rabbit. Include a picture and all relevant information about the rabbit, and charge a small adoption fee.
Advertising a rabbit as "free to a good home" is dangerous, as it may attract people looking for prey for snakes or dogs. Be sure to ask any potential adopters questions about their homes and how they plan to care for the rabbit. Consider doing a home visit or asking for references from a veterinarian.
Before you advertise the rabbit, spend some time getting it ready for adoption if possible. Get it spayed or neutered, and spend some time training the rabbit to use a litter box and to accept handling by people. A friendly, well-trained rabbit is easier to place than a destructive, difficult rabbit. Getting to know the rabbit's personality can also help you match it with a suitable home.
Contact rabbit rescues and ask them for specific advice or assistance as well. While many of them are often full, they may be willing to list your rabbit online or help you screen potential homes.