Rabbits shed every three months, so grooming is mandatory. Rabbits skin is very delicate so grooming is required, use a brush than isn't rough on skin. You should brush your rabbit thoroughly as least once a week, you should also trim their nails, clean their ears, check their teeth, and if needed clean their scent glands.

 With long haired rabbits, they require a lot more attention than their short haired cousins. I'd recommend that you use your scissors and keep their hair trimmed to one inch or less, otherwise you may be fighting hairballs most of the time.

Don't bathe your rabbit. Rabbits clean themselves and if they have a dirty bottom, take baby wipes and clean their bottom. 

I brush my bunnies once a week, I trim their nails once a week, I also check their ears, scent glands, and teeth. This also includes me doing an overall check to make sure their is no scratches, bites, or signs of illness Keep in mind, rabbits are great at hiding illness so if you notice something strange going on with your bunny take them to the vet immediantly.