What breed and how far through the whole process are you?
Get yourself set up with a mentor before doing anything, usually the go to person would be the breeder of your bitch. They can help you with evaluating conformation, health screening, studying pedigrees, looking at inbreeding coefficients, picking the most appropriate stud dog, care of the bitch during pregnancy, whelping, pretty much everything right up until the puppies leave. Books and online information sources are useful but really nothing beats having someone experienced on hand (either in person if possible or happy to be contacted any time day or night) to guide you through the process the first time and offer advice or support should you need it.
I would highly recommend using the Puppy Culture programme, it's the absolute gold standard of puppy raising and nothing will give puppies a better start in life. You can see a brief summary of the sorts of things involved on this breeder's site and there's also a Puppy Culture FB group but I really would either get the DVD or VoD so you can watch and re-watch as much as you need to.
The KC have some useful online resources including a novice breeder checklist and templates for various advice sheets, etc. which you may want to include in your puppy packs.
Start putting feelers out for interest in the litter within your breed/sport/working community fairly early on, it's preferable to have as much time as possible to vet potential new owners. Champdogs have a guide to breeding and selling puppies and a guide to interviewing puppy buyers which are both well worth reading. I'd also suggest looking at their guide to buying a puppy and the accompanying list of questions to ask a breeder so you've got an idea of what people who have done their research will be looking for in a breeder.
It's well worth getting set up on Champdogs (if you're breeding pedigrees, obviously) to advertise there, you can actually advertise planned not just those already on the ground. Once the litter is born you can also advertise them via the KC, again if they're pedigrees. Breed clubs will generally have a puppy list as well which the litter can be listed on.