Hi. Been breeding big ol meat bunnies (purebreds) 4 years, working in rabbits for 10 with pets and rescue before that.

Rabbit tractors work great for rabbits that are acclimated to eating greens. I love them as TEMPORARY (not permanent or overnight) day play pens... But you gotta be careful that they are acclimated to eating the species of plants that are OK for them before tractoring them, or else they might cow down on things that are not so good or get a tummy upset from eating a lot of fresh greens at once.
Hmm, ten things I wish I'd known.... Problem is, I think I knew most of the newbie things when I went into breeding. I'd owned rabbits for years before breeding and other animals for years before getting into rabbits... And rabbits aren't much different than other mammals. Since breeding rabbits I think these were my top ten things I didn't know...
I wish I'd known that rabbit vets tend to be useless unless you want spayed/neutered pets. In fact, even if you have pet bunnies they can be pretty useless. Vets don't know much about rabbits, frankly, and I've yet to meet a rabbit vet who cares more about the rabbits then the money they get for treating an "exotic" animal... But hey maybe they exist.
Buying rabbit toys is a waste of money. Make your own. They like the cardboard boxes you get your DVDs shipped in WAY more than the plastic houses you buy. I made 5 hanging chew toys in an hour yesterday. Get out your drill, scissors, a branch cutter and some twine. You can make dozens of toys daily with a little know how.
Dwarfism genes are something you need to look into if you wanna keep small rabbits. They do funky things to their hips and breedability.
There's no good options for having wire floors that have spaces smaller than 1"x1/2".
Not all hay is created equal, and 2nd cutting timothy or orchard grass is ideal. Pet store hay is EXTREMELY over priced. Have your hay shipped in in bulk from a local farm. I spend $75-$100 on delivery and $4-$8 per 50lb bale of hay. If I had only two bales delivered at a time I would spend $1/lb on hay. Kaytee Timothy Hay is $14 for 6lbs on SALE. That's more than twice the price. I have 20 bales delivered at a time (a years supply) and store them in my garage. That's around $0.20/lb. I could not imagine feeding rabbits on pet store hay, or even hay from somewhere like TSC where it's $15/40lbs.
Wal-mart is a terrible company, but if you run out of rabbit food, their house brand pellets are cheap and have decent nutrient values.
J clips are amazing and you should learn what they are and how to use them if you wanna make your own cages. Trust me.
Rabbits don't spook and die as easy as people say they do. My rabbits don't care if I use power tools next to their cages, or if my dogs go heckin borking their heads off. They acclimated to my daily sounds very fast and now don't care.
County fairs are usually a bad place to look for rabbits. People tend to bring some low quality rabbits there.
Pedigrees mean nothing, and they do not mean a rabbit is purebred or registered. A pedigree in rabbits is a scrap of fancy looking paper that a breeder put together on their computer. There's no overarcing registry like there is with the AKC for dogs, save for the ARBA registry of rabbits who are grand champion show rabbits which very few rabbits are. The pedigree system for rabbits is almost completely an honor system. If a rabbit "looks" like a breed and it's offspring look like the same breed, and it's parents look like that breed, they are considered that breed. People can lie on their pedigrees, or fill out pedigrees for mutt rabbits, or do whatever, with no reprecussions except for a poor reputation (if anyone ever even finds out). So tread carefully in that department. I had no idea that pedigrees were just filled out by the breeders and there was no registry for purebred rabbits like there is for dogs.