There are a lot of good feedbacks here and I wasn't bothered to read through them all, so here's the essentials. (ps. I have a college degree in interior design if that makes you feel any better)
1) KEEP YOUR SHIT CLEAN!
2) Get rid of alcohol paraphanilia (sp?)
3) Bed, Bath and Beyound, Ikea
- Get some lamps
- Candels for the bathroom and Living room
- Proper bed set and towel set (Make shit Match)
4) Book shelf with pictures (in frames) on it and books would help too
5) small, easy to take care of plants.
6) As you already have..... pictures and poster (Prints of famous art work or your own art work if you're artistic........) IN FRAMES! I can't stress the frames enough. Even if it's glass front no border frames....
7) Area rugs if you can find any good ones
8) Get a girl to help you decorate, a woman's touch can go a long way!
9) Make sure your shit matches
10) KEEP YOUR SHIT CLEAN!
Good Luck