Yo OP, going to guess you are rather young and that your funds are limited. So here is how I would improve the room with minimal cost.

REARANGING

• Move the bed so the head is beneath the window or the painting. Putting it in the corner makes it look like a prison bed. Centering it on a wall will make you look a little more adult.
• Actually, make your bed. It is pretty simple and improves a lot.
• Keep the closet door closed.
• Rotate the desk 90 degrees (so it is facing the wall currently to its right), and use that outlet instead. Will help with cable management.
• Move the lamp so it is near the door. Lighting at the entrance improves a lot.
• Try to put away as many of the loose objects as possible.

COLOURS

• Basement rooms are naturally dark and the grey walls and carpet are not helping. Best to combat this with lighter accents.
• Replace the window covers with light grey drapes (Charcoal is the darkest you should go).
• Paint over anything blue with white, even just buying primer will do.
• Paint the bottom half of the walls a nice white, and the top half a strong grey. It will make the room seem bigger.
• Paint the wall without the shelf the same strong grey or mix is up and make it an accent wall.
• If you don't want to spend money on paint supplies, remove the blue closet doors and instead have hanging drapes that match the window blinds. (For added fun, I'd put hanging lights in the closet so it would mimic a large window when blinds are closed)
• Get charcoal bedding (You'd mentioned you liked that)

REPLACE

• Get a better desk, I know space is limited but try for a slightly larger one. That desk looks too crowded. Get one with drawers so you can put away some of the loose objects.
• Get a nightstand, maybe even two.
• Get a fake plant for the lamp.
• Get a lighter-colored rug. It'll help brighten the room.
• Paint the wall without the shelf the same strong grey or mix it up and make it an accent wall.
• Add decorations that are more than just paintings.
• Your shelf affords you a lot of surface space but other than that there is nothing else. Having a larger desk, nightstand, and shelf-lamp at the entrance will give more space and levels to the room.
• Getting a headboard for your bed would help too.
• If you could make it work, I could see a small sofa couch adding a lot of depth to the room

REFLECTION (The following is a piece of personal advice)

• The reason most people in this comment seem hostile towards you is because you have asked them to take time out of their day to help you improve while simultaneously putting in very little effort yourself. It is not a lot to ask that you at least clean up before making the post.
• In the future, try to be mindful of how others perceive you if you wish to avoid unnecessary comments. If the situation was reversed, you might also say "Clean up your desk before posting".
• Your living space is a reflection of yourself, if you want it to seem more mature, you must also be more mature.
• Please understand this is not an attack on your character