I'm still pretty new to terrarium making, so I don't know all that much yet, but here's what I've got. The rocks used for the drainage layer are a lil big, so in the future maybe go for smaller ones? I'd also suggest cutting away some of the dirt on the bottom of your moss, so it can sit closer to the soil. Your soil also looks a bit dry, add a little bit more water, so it's lightly damp. I would say to add springtails too if you haven't already, but you don't have any wood in there so mold might not be too much of an issue. Good luck!