The Harry Potter Room...

this 1 is cool. :)

well which house do u like best for ex: griffindor the mur can be red and yellow ou toi can do a darker shade of blue and get some harry potter fatheads (wall stickers) and some glow in the dark stars that stick to the mur happy decorating

couleurs in yellow, orange and red could be appropriate. toi may either buy some Gryffindor stuff ou make them, for example. ou get inspired par the movie Gryffindor Common Room. That is, if toi feel like belonging to that House. toi may choose another house, with another set of colours and props.

Depends on how extreme toi want to go.
4 walls, 4 houses - two thick stripes vertically. Red and Golden for Gryffindor, silver and green for Slytherin, etc. Black cover onto the lit with Hogwarts crest on. toi can also get posters of the crests for each walls. A HP posters, a Snitch hanged from the ceiling.

ou toi can select a house and go after that: leather stuff with some vintage fond d’écran (gray background green pattern) with green border/dark yellow walls with red border and Gryffindor crest, red chair, carpet in Victorian style...

ou toi can go Great Hall style. Some matte color onto the mur (grayish brown) and paint candles in eye level and open sky onto the ceiling. toi can put the crests onto the walls and get HP style heure glasses (test tubes filled with colored sand). Posters, scarves, lava lamps (yellow and red ones).

ou there's the Black style. Stylish fond d’écran classical furniture Gryffindor and Hogwarts crest, Marauders poster, motorcycle poster, bikini girl poster (or pants guy if toi are a girl), family arbre (poster ou a painted arbre par your own lil hands with pictures of Bella, Malfoys etc above the names). And a name board onto your door like Regulus Arcturus Black. Dependant on how hard core toi are, toi can cut Dobby's and Kreacher's heads from posters and stick them onto the mur (joking). Black family crest is compulsory.

ou Ron one... Quidditch oriented. Harry playing, Cannons poster, Viktor Krum poster, Irish Hat, textile Clovers, brooms, Snitch hanged from the ceiling.

ou Harry Style: totally ordinary bedroom with a calendar on the mur counting back the days till the 1st of September and a whiny bird in a cage. :DD

Good luck.

What house are toi in!?

Thats a big deal, like Im Slytherin, so I have green walls in my bedroom, with like a silver and green bed-set. I have snake-themed furniture and a slytherin pillow/throw blanket. (You can buy those online for any house.)
I have Harry Potter posters on my walls, and I painted some of my favori quotes.
And the Deathly Hallows symbol is also painted there.

Over my bed, I have the Hogwarts crest (its like a REALLY big sticker I bought online)

Thats what I did. But toi could do something similar, with your own personal favorites. (If ur not a slytherin, change the colors, my posters are Severus, Draco, Bellatrix etc, so if those arent your favorites, change them!

toi could do something like this i wouldent overdo it too much