I'm still learning, but I'll offer what I can.
Pick out the most clean and perfect shaped eggs. No dirty or odd shapes.
Make sure they're normal sized eggs, if they're too big sized they could accidentally have a double yolk and be twins doomed to die.
Don't wash the eggs! That destroys their protective coating.
Make sure you collect eggs within 10 days, after that the hatch rate is so low it's not worth it. Store them around 60-70°F until you set them.
Store eggs with fat side up and turn several times daily, always turn an odd number so the yolk doesn't sit on the same side as it did the night before. (I wasn't very good at remembering to turn, but they still hatched so it's okay if you miss a few times) I set my eggs in an egg carton.
Make sure the incubator is clean and has been set up close to 24hrs prior to setting eggs. This way you know how consistent your heat will be and what your humidity is.
If you have an egg turner just set them in there, but if you don't you'll probably want to mark an X on one side of the eggs so you know which side to turn to each time.
You can candle after day 5, that'll be your earliest time to see any development whatsoever unless you've got a really good flashlight.
Personally I suggest candling at Day 12 or 15 to clean out "quitters" aka dead babies. Otherwise they may explode and kill your living chicks.
Day 18 is lockdown, that means you take out the egg turner (or just stop turning) and jump up the humidity around 60-70%. You can candle one last time to look for late quitters. Do NOT open the incubator at any time during lockdown.
Day 21 is hatchday! Try to resist opening to remove chicks until most are out. Unless you see the hatched chicks are bothering your hatching eggs. I did have casualties because I left chicks in too long and they rolled eggs around and got them all sticky, which the egg suffocated and died.
When I removed chicks, I had family help so one person held up the incubator lid and everyone else grabbed chicks. Then the process took about 3 seconds and no eggs were shrinkwrapped.
My tips are buy extra thermometers and hygrometers so you know how accurate your incubator is. I have an Egg-O-Meter... but it broke after 17 days and told me the temp was only 70°F when I know it wasn't. So I would go on Amazon.com and look at reviews of all the different thermometers and hydrometers.
I'm still trying to find one that works good.
Always ask questions if in doubt of anything! That's what we're here for
