You want to stay in the 45% range for the first 18 days (unless you are using the dry hatch method or the weight loss method and adjusting throughout). At "lockdown" on Day 18 into 19, the humidity should be increased to the 65% range. You can accomplish this using sponges or other substrates to increase the surface area of the water added. Once you get your first pip and hatch, the humidity will likely rise on its own. Good luck!
I'm not going to argue with the others. I agree with them that those are good ranges to shoot for the first time. You will get a variety of opinions on this topic. We all have different types of incubators and different conditions. What works for me might not work for you. What I suggest is try it, then analyze your first hatch. The links below may help you do that. Then you can make adjustments as required. Mississippi State Incubation Troubleshooting http://www.poultry.msstate.edu/extension/pdf/troubleshooting_incubation.pdf Florida Incubation Troubleshooting http://edis.ifas.ufl.edu/aa204
