Adorn your walls with art.

Just because you're older doesn't mean you have to give up on all those great, dated band posters that you grew up with. It does, however, mean that you have to take them off the wall and put them in actual frames.

Simply go to a crafting store and by the appropriately-sized frames for your posters, or make your own frames. Framed art on your walls makes your room more inviting and lived in.

In addition to framing your posters, consider putting other decorations on your walls, like clocks, mirrors, accents, decals, mirrors, picture frames, and letter boards. You should also think about the material; are you only using plastic, or can you mix it up with metal and wood?

Paint your walls.

Before you begin to put things on your walls, however, you should consider painting your walls so they're not just the drab white that came with the place. Wall colors help set a mood and create an atmosphere within a room.

Before you start slathering primer and paint on a wall, you should carefully think about what color scheme would work well in your bedroom and what colors would go well with your existing furniture—a grey dresser might look odd in a light-yellow room. It also helps to consider whether you want to go with classic colors, trendy colors, neutral colors, bright and bold colors, or dark and cozy colors in your bedroom. Avoid colors that are too childish, like bubble-gum pink or neon green.

Pot a plant.

One of the most adult things you can do is take care of another living thing, like a plant. In addition to being easy to care for, plants help reduce your level of anxiety, improve your mood, and purify the air in your household. Make sure your plans are kept an area where they can receive sunlight, if necessary, and that you keep them well-nourished. In addition to dying plants being a bad look, rotting plants can give off a terrible smell. Some of the best plants for your bedroom are lavender, areca palms, English ivy, rosemary, and peace lilies.

Put up some shelves.

A great way to display your various art objects, plants, and other memorabilia is to put them on shelves. Shelves are a great way to use the spare space on your walls, fill up your room, get things off the top of your dressers, and add texture to your bedroom. Wall shelves range in size and price, so it's best to gauge the number and weight of the things you'll be putting on them before buying your new shelves.

Think about your lighting.

While lighting in your college-era bedroom probably consisted of a plastic lamp and a light bulb hanging from the ceiling attached to string cord to turn it on and off, you deserve much more than that now. The way you light your room says a lot about the function of the room.

To light your bedroom up, you need to layer the lights in your bedroom. That means having different lighting for different moods and activities: Sitting in bed reading a book? That's a perfect ask for a bedside table lamp. Need lighting for making your bed or cleaning up? That sounds like a job for a floor lamp or recess lighting.

In addition to lighting fixtures, you'll want to think about choosing good bulbs, having smart lighting, and using dimmers.

Upgrade sleeping gear.

If you're still sleeping on the same sheets that you had in high school, you're doing it wrong and it's time for you to buy some new, mature bedroom linen sets, including pillows, blankets, coverlets, sheets, duvet covers, pillowcases, and throws.

Not only will an updated linen set make you look more mature, but it'll also help improve your sleep. In addition to looking into new linen sets, you should also consider buying a new mattress if you haven't changed mattresses in the last ten years, swapping out your pillows for a fresh set, and buying a bed frame with a matching nightstand.