The best way would have been have homes lined up before you bred your dogs. But since they are here now an airtight contract and to spay and neuter your pets before they leave your home or have strict guidelines for when it has be to done.
Check out a reasonable rescue site and see what THEY ask potential famlies. Ask questions, and just know that you don't HAVE to let any one HAVE any of your babies if you don't think they are right. I have had very few 'bad families' in the past 10 years, but no one ever wants ANY. That is what will keep you up at night.
Keep in mind, that any type of advertising will get good and bad prospects.
Here's my case scenario. Some contact me by email or phone. The next step is my application. I won't proceed without it. Some prefer to discuss it on the phone-which is great, some email it back. Then comes the interview. I keep notes from each conversation. Granted some people may say something different time to time, but I am always comparing notes from their previous conversations. I was able to weed out someone who wanted to add my lines to their 300 dog kennel. Now, I've always said that it's a breeders right to choose, but one person caring for 300 dogs is not right and I stand behind that!
Before the puppy is placed, I want them to feel they can trust me and I feel I know them. The vast majority, I meet in person, about 10% are sent air. Every single one of those people in person have hugged me and they email me all the time. That is really the only way a breeder can improve on things that are not covered in contracts, like temperment-is if you are in contact with them and they call you when they need you.
I have had 2 homes that were perfect at the time. I met them, met their other pets, their families, etc. Both of those puppies had to be rehomed, but they did come back here for me to rehome them and we've had wonderful success in their new homes. So even if you've tried so hard, there may be a few. Remember, people's circumstances change and you rehoming is the best thing you can do. But people need to understand, that rehoming is not refunding at Walmart. It's not a 'well, a dog is just not for us' deal. I really grill it in their heads that my breeds will live this long if all goes well. This is what to expect from this breed. This is what will happen to your home. It almost seems at times that I am trying to talk them out of it, but I want them to understand upfront.
And, in closing, the most important thing to remember is to be upfront-these are my expectations, what are yours. IF there is a problem, don't point fingers-get solutions, help them, talk with their vet. People are so surprised in this world when they have a problem, that someone is willing to help without blame and really listen and understand.