Living alone here. First, I've learned PLENTY about how to be frugal and keep your head above water. Went thru bankruptcy about 5 years ago now, got in heavy with the credit cards when I was younger. I vowed after that to live within my means, and no matter what - NOT live paycheck to paycheck.
First off, do what you have to do to BUY - not rent. Renting, yes, is a part of life, but should really be as temporary as possible. I finally just bought my first home. Bought a HUD foreclosure. it's not perfect, but for a first home.... My mortgage isn't much more than half what I was paying in rent. Once the house is fixed up enough, I'm going to rent out a room. That will cut my mortgage down to near nothing. I have a BASIC cable/internet package. I found a deal with a 2-year contract from Comcast (nobody else services my house here :/). $39.99/month for their crazy fast internet, and basic cable. I have a cell phone and pay $45/month for that for unlimited talk/txt, and 500MB of 4G web (throttled back to unlimited 3G after that). I have wifi at work and home, so the web is no issue for me.
As other shave said - be energy conscious. Turn stuff off when you're done with it. Spend the ~$50 on a programmable thermostat to turn the head down while you're gone, and have it set to automatically come on before you get home. Worth every penny. As others also said, buy in bulk, but BE SMART ABOUT THAT - DON'T buy things in bulk that go bad that you, as a single person, won't have time to eat. And don't buy large things in bulk that you end up going thru faster just because you happen to have them on hand.
Find a hobby. Something to occupy your non-work time. I play with cars. Sometimes it makes me money, most of the time it costs me money. I fix them, build them, race them. I now teach defensive driving & car control, and am a volunteer in-car instructor for Street Survival, a teen defensive driving program sponsored by TireRack & the BMWCCA Foundation. We're all MUCH happier people if we're productive than sitting around, and that productivity doesn't always have to = making $$$.