I need help with humidity

Hi, I’ve been having issues with keeping the humidity high inside my enclosure.

In a few days I’m supposed to go get my gecko (everything is ready), the only issue is that my humidity keeps being around 50%, with peaks of 60/65% as soon as I mist.
I know it should be higher and I need some advice on how to do it.

I use a coconut soil which should retain more moisture and I also ordered some moss, as I read it helps.

I want to make sure the gecko won’t have any issue so please any advice will be helpful!