Moving to San Francisco in July for work. Where should I live?

I am a 24 year old (about to be 25) recent college graduate. I work for a large financial services firm that is basically located downtown, but I will also be traveling a lot. I don't mind having roommates (as long as I have my own room). I guess my budget is about $1,250/mo, but I'd rather explore all my options before setting a fixed price. Any ideas, redditors? Ideally the place would be safe, clean, and young!