Most important thing is to learn how your incubator behaves for a few days to a week BEFORE you set eggs.
Temp spikes kill.
Slightly lower temps are not as deadly as temp spikes.
Too high humidity will cause problems.
Which bator do you have?
Any can work...as long as you calibrate one thermometer you'll know how off the incubator is reading. I keep 4 or 5 thermometers in my bator at all times.
Humidity gauge...salt test it before you set eggs.
Flashlight...small is better. 750 lumens works well.
I have a few of these:
Zacro LCD...
Welcome! I can usually tell if my eggs are developing by day three.
Do you have a calibrated thermometer and humidity gauge in your incubator?
A bright flashlight?