I like the personal touches, that mean something, like the Grease poster...
You want decent seating in your apartment. Or some really big comfy pillows that allow for sitting on the floor.
Good lighting. (overhead lighting is bad -- lamps are good)
If you expect company of the female persuasion:
For your bed.... Nice quality sheets (
www.overstock.com or
www.domestications.com has nice stuff that won't break the bank. and decent towels.
Other people's cast offs are a good start for people starting out, but rather than dumpster diving, check out a site called
www.freecycle.org - it's a mailing list for your area, that people will list stuff that they are getting ready to get rid of - -in my area a lot of folks are ditching furniture.
They list it -- you go fetch what ever tehy are dumping.