Pose-wise things look very nice indeed, once you get some shading down you’ll be golden. I would say some kind of Tie-in or either contrast between the formal shirt & tie suited design and the space elements would give it something a little extra to tie it all together nicely.

You could execute it with just the colouring and shading but that might be too tricky, just focus on the shading, maybe consider a central light source for how you might go about the shading and that should do it. Maybe throw in some shooting stars circulating around the space dude.