What I used to do at college and also if I'm traveling is tear glossy ads or fashion shoots from magazines and frame them in the glass frames you get from the dollar store. Just cut them to size and you have some nice and glamorous pictures. I quite like the fragrance ones and sometimes beauty counters have postcards and I frame those as well.
Just out of curiosity, how big is your dorm room? Are you in a single dorm room or are you sharing your room with other students? I was in a single dorm room when I attended Ohio University back in the 90's and it was practically the size of a walk in closet. Once the bed and the desk and my mini fridge were in there, I literally had about 2 feet x 4 feet of walking space. I'm not kidding when I say that I carpeted my the linoleum tile in my dorm room with a door mat from the dollar store. Speaking of dollar stores, places like Dollar Tree have lots of really nice frames in there, for only a buck. That's cheaper than what you would pay at most thrift stores. So if you've found a lot of images that you like you can certainly get them framed for cheap. Another cheat so to speak, is to check out some art history books from your local library, and head over to your nearest FedEx Kinkos, and simply make some color copies and enlargements of particular artwork that you like, then frame it. Technically this is probably illegal, but it's highly unlikely the store associates are even going to notice or care. There are battery powered tea candles, and battery powered regular candles, which could give your room some nice ambiance without putting you at risk of something catching fire. Students rooms catching fire due to candles is rather common on college campuses unfortunately. Plus if your dorm room is particularly small you may not want all the heat and smoke from real candles. If you've got a decent sized window sill, you may be able to grow some small potted plants in it, which will help clean the air in addition to adding some decor to your room. You might not think of a place like Dollar General, but they often have small pieces of furniture in there too, it's usually stuff you have to put together yourself, but it can look nice too. One time I was looking for some small cherry wood colored end tables to put on both sides of my bed, which had a cherry wood colored head board. I lucked out and found two double-tiered cherry wood colored plant stands for only $6 each which matched perfectly.
I like to save the pretty pictures on calendars and use them as decor in a room. I don't always frame them because of them are large, I like the oversize of the picture. I will find pictures of flowers or scenes of the sky and use them to bring some color to a dull room.
All these ideas are so great. I will add that now days, there are some fabulous fabrics with artistic patterns and even pictures and scenes, that can be framed and will add interest to any room.
Plants can liven up any room. They shouldn't be only on the window sill. Place potted plants all around your room and it will most certainly look better. You needn't spend a lot of money on the plants. Buy seeds [they wouldn't cost a lot] and plant them yourself. Or you could get a plant or two from a "gardener" you befriend.
My old dorm room was fairly big (in the UK) but I have seen some tiny rooms. As for window sill, to be honest my windows were always open because of parties and people climbing in and out, so plants were never a good idea. Plus you do need to take care of them and if you are a party person then maybe not. I also used to keep nice photos from calendars and frame those. For those that can't use blu-tack or hang things, you can use a large pinboard.
Hmmm... You can buy indoor plants. There are many low-maintenance plants that you can buy at Walmart.
