Get a few things to organize your room.
Rolling file next to your desk for papers/homework.
http://www.walmart.com/search/search-ng.do?search_constraint=4044&ic=48_0&search_query=your+zone+on+a+roll+storage+cart
Baskets for beauty items.
http://www.walmart.com/search/search-ng.do?search_constraint=0&ic=48_0&search_query=willow+basket+set+mocha
Pocket organizer you hang over a door for shoes, gadgets, odds &ends...
http://www.walmart.com/search/search-ng.do?search_constraint=0&ic=48_0&search_query=over+the+door+pocket+organizer
Storage ottomans -plus extra seating
http://www.walmart.com/ip/Homz-Kidz-Small-Storage-Ottoman-for-Girls/12177636 - set of two 16x16"
Hanging a mirror opposite of the window will brighten your room and make it appear larger.
http://www.target.com/Wall-Mirror-Pink-25-5x15-5/dp/B0015EEWDQ/ref=sr_1_1?ie=UTF8&searchView=grid5&qid=1275654475&frombrowse=0&fromGsearch=true&node=1038576%7C1287991011&keywords=25.5x15.5%20mirror%20pink&searchSize=30&id=Wall%20Mirror%20Pink%2025%205x15%205&searchBinNameList=purchasing_channel%2Csubjectbin%2Cprice%2Ctarget_com_primary_color-bin%2Ctarget_com_size-bin%2Ctarget_com_brand-bin&searchNodeID=1038576%7C1287991011&searchRank=target104545&sr=1-1&searchPage=1&rh=
You could drape a feather boa with fairy lights over the mirror.
http://www.funkylighting.com/index.asp?function=PRODUCTIMAGEWINDOW&closedelay=20000&SRC=http://www.funkylighting.com/ekmps/shops/funkylighting/images/fluffy-feather-garland-boa-for-use-with-our-led-string-lights[ekm]133x100[ekm].-pink-white-or-black-[3]-139-p.jpg - target has them in pink and purple for $13
Hang a panel between your curtains.
http://www.walmart.com/search/search-ng.do?search_constraint=0&ic=48_0&search_query=groovy+sequin+curtains
Memo board above your desk.
http://www.etsy.com/shop/kayskrafts?section_id=6799921
Easy and inexpensive to make one.
Cut a rectangle out of box cardboard 16x20" or any size you like.
To make the hanger, punch two holes 1/2 inch apart 1 inch from the top in the center,
thread the ends of a twisty-tie (paper covered wire used to close bread) thru the holes, turn cardboard over, make a loop and twist the ends together.
Cut a piece of fabric two inches larger than the cardboard.
Lay cardboard on top of fabric, run a bead of elmers glue around the edge of cardboard and wrap fabric to the back like a present and glue down the edges/folds. You could add ribbon in a geometric pattern or use push pins to pin up notes, photos, cards...
You can get 1/2 yard (18x45") of fabric for about $2 in tons of different colors, patterns and designs at any fabric store or in the sewing section of department stores-walmart/kmart
or you can use a colorful shirt you/mom don't wear anymore or one with a cool design.
Poster on a spacious wall.
http://www.postersbyimpact.com/store/pc/viewPrd.asp?idcategory=0&idproduct=626 - free shipping
http://www.postersbyimpact.com/store/pc/viewCategories.asp?pageStyle=h&ProdSort=0&page=4&idCategory=13 " ^ "
Check http://www.postergods.com/ for 1/2 price movie and music posters.
Print close-ups of beautiful flowers and hang together in matching 5x7 frames.
You might like a couple of these.
http://img205.imageshack.us/img205/9342/purple20foxglove.jpg - click file, print with preview, size 5x7, print
http://g1wallz.com/wp-content/uploads/2009/04/red-flower-black-butterfly.jpg
http://upload.wikimedia.org/wikipedia/commons/3/31/Stargazer_Lily.jpg
http://images.flowers.vg/1024x768/iris-purple-yellow.jpg
Or make them into mini canvas's
Cut cardboard 1/2 inch smaller than the flower pic.
Make the hanger.
Lay cardboard on top of the back of the pic, run a bead of elmers glue around the edge of cardboard and wrap pic to the back like a present and glue down the edges/folds, turn over and weight down till dry.
Homemade Designer Frames
Cut out any size frame from box cardboard, make the hanger and wrap with fabric strips or gift wrap and glue pics to the back so they're facing forward.
http://tlc.howstuffworks.com/family/fabric-crafts5.htm - wrap like the picture
Wall Decals
Use contact paper ($5 roll) easy to draw and cut out any shape or design,
just peel & stick, easy to remove without damaging walls, plus reusable.
http://www.threadbanger.com/decorityourself/episode/DEC_20080520 -watch til end
These might give you some ideas.
http://www.dezignwithaz.com/
http://www.pbteen.com/products/round-paper-lanterns/?pkey=x%7C4%7C1%7C%7C6%7Changing%20paper%20lantern%7C%7C0&cm_src=SCH - 19" w/cord $21 free shipping
http://www.target.com/Flameless-Tealight-Candles-Glass-Votive/dp/B001CLFP1A/ref=sr_1_3?ie=UTF8&searchView=grid5&qid=1277743225&frombrowse=0&fromGsearch=true&node=1038576%7C1287991011&keywords=flameless%20candles&searchSize=30&id=Flameless%20Tealight%20Candles%20Glass%20Votive&searchBinNameList=purchasing_channel%2Csubjectbin%2Cprice%2Ctarget_com_primary_color-bin%2Ctarget_com_size-bin%2Ctarget_com_brand-bin&searchNodeID=1038576%7C1287991011&searchRank=target104545&sr=1-3&searchPage=1&rh=price%3A0-1499
Kmart has lava lamps $5 cheaper than target
http://www.kmart.com/shc/s/search_10151_10104?vName=For+the+Home&cName=Lighting&keyword=lava+lamps&sLevel=1
Go through your closet and dresser, clothes that are stained/torn throw away,
any that don't fit/wear give to friends/sister or donate.
When folding and putting the clothes you want to keep in your dresser, put socks and undies in the top drawer, shirts in the next, then jeans and sweaters in the bottom.
Hang clothes the same way, tops, then slacks, dresses, jackets...
Hang what you only wear occasionally to the back of your closet.
If you have a lot of clothes pack away winter clothes in boxes and slide under your bed and when the cold weather comes switch and pack away summer clothes. Once your seasonal clothes are packed away you will have a lot more space.
Clear off your dresser and organize your desk, use a jar or glass for pens/pencils and markers.You could wrap a shoebox with gift wrap for extras, crayons, erasers...
Stack game disks/dvds/cds.
Make sure you have a wastebasket and hamper.
We all have bad habits, leave things lay, flip our shoes off, throw clothes over a chair or bed/floor, leave clean clothes in the laundry basket...
To keep your room clean and neat get in the habit of doing things right away.
Make your bed when you get up, easy to just pull your comforter over.
When you're done using something put it away.
Throw away paper, snack bags and bring dishes to the kitchen.
Put dirty clothes in your hamper right when you take them off.
Fold and hang clean clothes fresh out of the dryer, no wrinkles and no more searching for clothes.
Then there's no cleaning except vacuum and dust when it needs it.
You'll love walking into your room all neat, organized and clutter free.