I started hatching eggs back in 2010. Didn't think it would be difficult. A slap-dash approach didn't work well with one chick sticking to its shell. Hand rotated eggs. Guessed humidity.
Next I built a better incubator and did two hatches in 2011. Typical inexpensive plastic bin 20"x14", insides and bottom having half inch foam home wall insulation and insulated top having a two pane viewing window, inside divided into 2/3rds for an egg shifter and 1/3 for electronics, warming 60 watt bulb, fan, divider between the hatching area and the back third, Circuitry keeps the temperature fairly stable. Cup of distilled water in incubator section for first 18 days then a pan of water for the last 5, pan of water having on top a wire mesh for the eggs to sit those last days.
Six egg shifter rocks every 2½ hours for the first 9 days then every 5 hours for the next 9. Has alarms for: a) failure to shift eggs, b) take data notification beep if wanted.
I'm presently wondering about humidity. To get a more even temperature distribution among the eggs, which I shift daily, I'm going to increase the fan rate. But, I'm worried that I might dry out the eggs with the increased air movement.
I have an IC (LM34) at the air intake before the warming lamp which dictates the lamp off/on and feeds a digital temperature reading on the external electronics enclosure. I also use Springfield Precisetemp temperature/humidity meters, of which I have a few (they seem to read temperature a bit high). Their humidity sensors seem to go bad easily. I have one where I removed the temperature sensor and humidity sensor and put those in the incubator on 28 AWG single strand wires twisted. The humidity sensor failed again and I've just ordered a replacement from Digikey. The meters are no longer available and I pretty much like them so I will keep repairing.
As I mentioned I hatched eggs in 2010 and 2011, mostly BFCM and some RIR. In 2013 I bought 4 RIR hens from TSC. All four turned out hens thankfully but only laid eggs for about 2 years. Meanwhile two of the BFCMs were still laying as the RIRs egg rate fell to a very few. Understandable, a store would want to sell chicks as often as possible. Last year one of my feed stores had sex-linked chicks all the same color so I mistakenly assumed they were all hens, but no, it was a straight run and wasn't told. I bought 2 but they turned out to be cockerels as did 3 more I bought from another source. Bought 5 chicks and all cockerels. I have only one hen laying now, a BFCM, older than any of the RIRs. She's been my absolutely most dependable hen. Old as she is, I'm going to try hatching her eggs. The old man roo, one of the original BFCM,s tends the hens well but I'm putting the one hen in with a young sex-linked roo - that one keeps trying to screw my foot. It's a gamble. The laying BFCM hen showed a white feather late last year.
I've tried candling without success as the BFCM eggs are so dark.
I live alone and keep my eggs. When I was getting too many I'd take 3, put them in a Handy Chopper, osterize them well and pour into cleaned Boost Supplement jugs, date and freeze. I started consuming them last winter and ran out earlier this year.
Right now I'm debugging my incubator and egg shifter electronics - they got knocked around a little these last few years. I'll start eggs in a week or 10 days.