Hint for first timers.
Pay close attention to the size of the air cells in your eggs. Candle right before you put the eggs in to see how big the air cell is at starting. Take a picture if you can. When you candle at day 7, look to see how much the air cell has grown. If it hasn't grown much, lower your humidity. If it has grown a lot, raise your humidity.
I used the Dry Incubation method with my first set of eggs, and while I got a 66% hatch rate with shipped eggs, I think it would have been higher if I'd upped the humidity a bit for the second half of the incubation period. Shipped eggs are generally a little old so they'll be a bit on the dry side anyway, and if an egg is porous as well it loses moisture faster. I got some nice Lavender Orp eggs for my second go-round, and they're rather porous. I've kept the humidity 15% higher on average than my last incubation, and the air cells on some still look like they're growing too much.
You'll see people advocate for both high and low humidity averages, but the most important thing is how much humidity your eggs need. And that varies from egg to egg and batch to batch. Watch your air cells.