-Start thinking of a narrative for your room. What kind of facility/ship is it in? Who's using it? You're a good stage to start adding clutter and details, and those will really help sell your story and make your room a lot more believable. For example, you have a gun rack, but this appears to be a single room and there's no way a single dude will carry three identical sniper rifles. In addition, there's nothing yet that really "sells" that your room's occupant would have a gun rack. If they're a mercenary or soldier type who keeps weapons in their room, think of the kind of stuff they'd have with it. Cleaning kits, boxes of ammo, medical supplies (for when they get hurt), maybe a disassembled weapon they're tinkering with on the desk. Look at the picture I posted above - it's a different theme from yours, but it tells a story: the guy in that room is obsessed with data, he's a scientist, maybe a biologist. There's a bunch of tanks with animals, plants that he's studying, and you've also got computers, notes that he's been taking or newspaper clips, on the walls, scattered all over the floor. You can also see the guy is super messy, has stuff lying about everywhere, garbage bags (maybe filled with salvage?) What's important is it's all /cohesive/, it fits together to tell a story rather than being randomly there.
Btw, remember to do a block in of your clutter/furniture before detailing it, so you can make sure it fills the room properly rather than being a bunch of objects that are too tiny or look like they don't belong.
You're doing great otherwise, keep going! And if you already know any of the stuff I've just said ignore me.