I just answered a similar Q yesterday,,,and lived 6 years in NYC attending NYU. I was in the East Village, in a basement apt. likely 400 sq. ft. approximately.
Downsize your life, but not your ideals.
Modest, minimal, are two words I'd use.
Size furnishings to be comfortable, yet not things you'll fall over in the dark. Stay away from more furniture than you actually need.
You might even look into some type of fold up bedding,,, but personally I detest Futons. Create lighting from above, not with floor or table lamps. Shelving EVERYWHERE.
Because it's a small place, and your time there actually will be spent in a very small space,,,IE: Chair, bar, stool etc, doesn't mean it has to be anything but SMALL in appearance. It can still be crafted to your tastes, and decorating it can be with prints to hang, colors of paint, carpet, a decent but modest entertainment system,,,etc.
I told the person who asked a similar Q... It may have been a small apartment, but just outside my door was ALL of NYC.
40 plus years as a contractor,,,still miss NYC