Here's what has helped me the most.
Have the incubator set up and running at the proper temp and humidity at least a couple days before the eggs go in. That way, the eggs should have a consistent environment from the beginning.
Do not candle. As far as I can tell, there is no good reason. I doubt exploding eggs are much of a problem if the humidity isn't too high and if they aren't going to hatch, candling won't help, but it might hurt.
Use a fan in the incubator. Temperatures can be far more consistent from edge to edge and top to bottom with a fan. This was a biggie for me.
Raise the humidity on the last 3 days to 70%.
Do not open the incubator unless you have to. The process of hatching can easily take up to 24 hrs from piping. Give them time and don't keep opening the incubator to remove the chicks individually.
Trying to help them out of the egg usually doesn't work. If they can't get out, then there is probably a good reason and the chick is likely to not do well. Eventually, normal chicks will get out on their own.