You can also do dry incubation, which I do. I add no water and the humidity stays around 20% or so the first 18 days. I will mist them once or twice during incubation with some incubation disinfectant. Then on day 18 I bump it up to around 65-70%.
It depends on where you live, how much the relative humidity is in the room where you keep the incubator.
Everyone has a different opinion on humidity and you will decide what works best for you. Alot of people will say that 50% is too high, but that must work for xxkiki.
Do some research. There are alot of good threads in the sticky at the top of Incubating & Hatching Eggs.
I myself learned alot from the Humidity Issues thread, and found that, in my situation, 30-40% for days 1-18, then 65-70% for lockdown worked well.