Using the right lubricants for things that move and are supposed to continue moving is very important. WD-40 is usually not this lubricant. To me, it's for breaking a nut/bolt loose and even then, there's better stuff.
I had extremely squeaky hinges on my studio door and I had tried a teflon lubricant, but that eventually dries up. It turns out that all I needed was sewing machine oil. Just a few drops and working it in. Those hinges haven't made a peep in weeks.