I thought it would be fun to make an article that I could point to rather than re-typing all the time
Firstly, breeder nutrition. Almost all of my birds typically eat our store brand meatbird crumble, which is 21% protein and includes animal protein. I feel this is very important. There is also grit, oyster shell, and clean water available at all times.
Secondly, I discourage hens from sleeping in nestboxes and make sure that any accidental fecal matter is removed ASAP. I cut 2x2 sheets of berber carpet tiles I get cheap at the home improvement store into four and use those in the bottom of the nests for a little cushioning, and bed with clean shavings.
I collect eggs daily and they go pointed end down in clean cartons. I keep those in the basement near my incubators and tip them morning and night, by propping something under one end of the carton, and switching ends. Sometimes, if I'm collecting from a lot of hens at once, I will plug in a spare egg turner that I have and put the eggs directly in there to turn as they wait to be set.
Cleaning and sanitizing: I choose to never set a dirty or unsanitized egg. If an egg is dirty, I will run it under hot tap water until the dirt will come off with a gentle touch. This I will do before I even put the egg in the carton. Before I set the eggs, I spray them thoroughly with sanitizer and let them dry, then they go in. If I'm holding eggs for more than a few days, I will spray them more than once to help keep their humidity up. My sanitizing spray consists of half water and half original gold Listerine.
I start my incubators a day or more before I plan to set eggs because I know that they are calibrated and I know that they will reach temperature quickly. It's good practice to fire up a week in advance generally. I run a GQF HovaBator 1602n with a wafer thermostat and a GQF 1588 digital, both with fans and automatic, upright turners. I incubate in the 1602 and hatch in the 1588 because I trust digital less than the wafer. If you have purchased a brand new incubator with a wafer, please message me and I will help you break it in, as it will not be ready out of the box.
Temperature: I aim for the heating cycle in my 1602 to range between just under and just over 100 degrees Fahrenheit. It stays set there because I only incubate chickens so far and I don't generally hatch in it. I aim for around 99 degrees in my 1588 because I'm not as worried about it being perfect for hatching, the chicks themselves are giving off some of their own heat.
Humidity: I generally do not dry hatch. I use a wet bulb thermometer and aim for that to be 84-85 degrees, giving me roughly 54% humidity. I like it to stay between 50-55% for incubation, which is what the universities mostly recommend. I don't panic if it comes close to 60% for a day, though I do adjust it so that it will come back down. Running the entire hatch at or above 60% will give you a higher percentage of chicks that fail to make it out of the shell and have died very close to hatch, or during. Running too dry will also cause defects in chicks and can result in them shrink-wrapping, or failing to hatch because they've lost too much moisture.
Measuring temperature and humidity: I use a wet and dry bulb system. That means I have two, dial food thermometers (not digital) that I have stuck through the side of my styrofoam incubator, one at the level of the center of the eggs while in the turner, and another below. The top thermometer goes in as-is, the bottom one gets a wick attached to it that is then draped into the water well. The bottom one is the wet bulb, and what that does is draws moisture into the wick and onto the thermometer and gives a reading of the ambient humidity, once you translate from degrees to percent. You can find wet bulb charts online by Googling "chicken wet bulb chart." For instance, when my dry bulb (the top one, reading the actual temperature inside the incubator) is 100, and my wet bulb is 84, the chart tells me the humidity is 54%. Note: this doesn't work that well with the yellow upright GQF turners, you either need to put the wet bulb somewhere else or drill a hole in the turner arm. To be honest, my 1602 is so stable that I basically only use a wet bulb once it's up to temp.
Thermometers: they need to be calibrated. I used to use the ice water and boiling method, but have since moved on to aart's method of using a human thermometer and hot tap water. She has written an article on how to do this that you can search.
Water: I use lukewarm water. You can use cold if you're just adding a bit, or when you're warming your incubator up, it will just take it a bit longer to get to temperature. If you're adding a lot, I might not use cold. However, do not use HOT water from the tap, the oxygen is different when it's hot and it's just not the best idea. You can use distilled water if your water is hard and you don't want mineral deposits building up in your trays.
Candling: many people like to candle every day, or every few days; I do not. In my book, the less the eggs are moved/touched/handled and the less bright light exposure, the better. When I'm hatching my own eggs or other brown eggs I trust to have been fresh and well-handled when I got them, I only candle on day 18, just before I put them into "lockdown." With a good candler and low light in the room, you can candle an entire 42 egg tray rapidly, the only thing slowing you down being however many you have to remove. A good egg will be totally dark except for the air cell, a bad egg will either glow bright like a lightbulb or will be half-empty or more. If you are hatching blue/green eggs, or eggs that were handled questionably, it's a good idea to also candle on day 10 to remove duds since blue/green eggs are naturally more porous than other colors, thus they are more susceptible to bacterial overload. I always run an alcohol wipe over my candler before starting.
Vents/vent plugs: I do not use plugs, ever. If your area is exceptionally dry, you may want to use one initially, but I cannot give any advice on this as I never do it. If you use them, make sure they're all out at lockdown and beyond. If you leave the incubator plugged during the hatch your chicks can suffocate to death from lack of oxygen. Also, before every hatch check the vents in the bottom of your incubator to ensure they are clear. Sometimes bits of shell or small styrofoam balls can be lodged in them, these need to all be clear in order to pull air up and over the water tray to ensure proper circulation of oxygen and humidity.
Lockdown: I lockdown on day 18, but will on day 17 if my schedule dictates, this makes no real difference. Eggs can technically stop being turned anytime after day 12. In my HovaBators, completely filling the bottom well *without* the tray installed will give me roughly 65% humidity in my location. I use five wide mouth canning jar rings, one in each corner and one in the center, and then place my floor grid on them; they're the perfect height. I also found a plastic floor grid from a poultry supply online and really like that, though the hardware cloth ones are totally fine. I do NOT place anything else in there on the floor, like paper towels or even cabinet liner. I find it works best that way to make sure the air can truly circulate freely. I also run a short length of aquarium tubing through the grid into the well, and notch it into the turner cord notch. This way I can add more water through a 60cc cannula tip/dosing syringe, without opening the incubator.
Hatching: Personally, I am hands-off. I typically won't even look at the incubator until day 22. I also use pieces of cardboard cut to fit over the windows so that it's dark inside, light will excite chicks and they're more likely to bump the other eggs around. When I'm satisfied that the hatch is over, I remove the chicks. I do not open to remove before I have decided the hatch is over. Occasionally I will let any non-pipped eggs go a bit longer after I've removed the chicks, but if these do hatch I mark them as not to be used for breeding as I don't want to propagate weak genetics.
Don't ever cover the incubator with something like a blanket or a towel, you can block the airflow and that's not something you ever want to do. If you lose power and want to keep the incubator warmer, you can carefully arrange towels or blankets, but pay attention to the vents on the top and bottom and keep them clear.
Chicks: the chicks go into my brooder, which happens to be a Pack N Play for children I picked up cheap. I line it with puppy pads and hang a heat lamp over it so that the floor is about 90 degrees the first day. They go in with only plain water until I'm satisfied they've all drank, usually a few hours. Then I add the feed in a long thin plastic feeder with the lid that hinges open and closed, with eating holes. Initially, I leave the lid flopped open and sprinkle a bit of feed on the floor. Once they find the feed well, I close the lid. The heat lamp is then adjusted in relation to the chicks behavior: huddled together I will lower it, avoiding it I will raise it.
I usually keep the chicks in the basement for about a week, and then they go into my large brooder in the barn. I plan to make a wire floor for that which will be even better; keeping chicks away from their own excrement goes a long way in preventing coccidiosis. I also feed medicated feed, currently 28% turkey starter for the first 8 weeks and then my regular meatbird crumbles after.