Set up your bills to pay automatically; that way you never miss a payment. In the same vein, pay all bills you get that might not be monthly--doctor's bills, etc--as soon as you get them. It's shockingly easy to set a bill aside and just forget to pay it. Be careful about the number of seemingly cheap monthly subscription items that you sign up for. Hulu is cheap on its own; so is Spotify or Netflix, but by the time you're subscribing to all of them you're spending an extra 50+ dollars a month. Finally, you haven't specified whether you have a car, or what part of the country you are in, but in any major city, parking can easily become a hugely significant expense. Your car will cost you about a billion dollars, so save save save for the day when they tell you "Surprise, you need to replace your suspension!" or whatever.
A lot of people have posted in this thread and PMed or repped me with stuff so just wanted to say thanks to everyone for the advice and although I have another month before I get cut off from the family funding it has helped relieve some of the stress already.
I graduated exactly a year ago tomorrow so I can definitely relate to this post. Bring a lunch to work. Assuming you're going to be in a city, you will have hundreds of options for lunch each day and that shit adds up fast. Make a sandwich that morning, make extra for dinner the night before so you have left overs, etc. Everything else that was new to me after graduating seems to have been covered pretty well. Additionally, if you don't have any roommates, I would suggest against getting cable TV. Thanks to the power of the intertubz, you can watch most stuff online. Picking up an HD antenna will get you the basic channels in HD, which is pretty awesome because between that and ESPN3, you can watch a decent amount of games without having to pay for cable.
I'm actually a first semester freshman in college, but I'm 23 and haven't lived with my mother for about 4 years. I consume a lot of time finding ways to save money. Here's a few I think haven't been mentioned yet, but that's because they're a little strange. 1) Buy/Sell/Trade- If you happen to own clothes/shoes/accessories that are in good condition and you have no need for, sell 'em. If you have especially coveted items, use ebay. For other things, places like Beacon's Closet or Buffalo Exchange will offer you 50% store credit or 30% cash for whatever they sell your stuff for. They pay you the day you sell them, not when someone else purchases your item, meaning this is a quick way to make cash when you're strapped. It's also a good way to recycle your wardrobe every few months, which may be important to you if a) your job relies somewhat on appearance, and b) if you're going to live in a tiny apartment with minimal closet space. I purchased brand new John Varvatos leather dress shoes for the boy for $35 at Beacon's closet, which I think is 90% off what they normally cost. Work shoes- done. 2) Coupon codes- This is the fucking internet, if you need to buy something from bed bath & beyond, google "bed bath & beyond coupon". Sites like retailmenot keep a running list of coupon codes for in-store and online purchases. (Btw, Bed Bath & Beyond offers 20% off any item if you sign up for their email. Hellooooo Sodastream) 3) Dealsites- Most people have heard about Groupon and livingsocial, but Googleoffers, Gilt city, Bloomspot, dealsurf, dealfind, dailycandy and kgbdeals also offer local deals on just about everything. -For food: Restaurant.com, where $1 will usually buy you $25 at several local restaurants, and Scoutmob offers 50% off featured local restaurants. -For apparel: Ideeli, Hautelook, Plndr, Gilt, Refinery29reserve, Jackthreads, (some are gender exclusive) - For luxuries- Lifebooker and Spasally (mostly spa/fitness related deals) - Also, Soap.com sometimes offers 50% off boring (but necessary) things like dishwasher detergent, papertowels, etc. Stock up when you see them cheap, because damn do I hate having to run to Duane Reade to pay extra for one fucking bottle of dishsoap. Bottom line- there is no need to ever pay full price for anything in 2012. Businesses have to compete with each other buy putting up deals frequently, so take advantage and save money on the shit you would have bought anyway. Addendum Before I got walletsmart about living, my seamless web account would routinely hold upwards of 20 orders a week, averaging $25-$30. Fucking hell, that's depressing.
To add to what crazy asian said, if you do buy anything online, go through ebates.com and you get cash back on your purchases. It's not much, but it's nice to get an extra $10 or so every month. Right now, they're doing 13.0% cash back on most stores because it's their birthday month.
A lot of good advice here, but I will add one that got me into trouble when first out of school. It is not the large purchases that run you into debt. It's the little things that you don't account for like buying a coffee everyday, videogames, movies, etc. that get you into trouble. A lot of folks will give you the save money by bringing your own lunch advice, but the truth is that doesn't do you a lick of good if you just spend that money in another way and don't account for it. At this point in your life every nickel matters and can save you some pain later on. Secondly, take advantage of your company's retirement plan if they offer one. If they have a Roth 401(k) even better, and try to save money to go into your own personal Roth IRA each year. Doing this now could allow you to retire a full 10 to 15 years earlier than you probably thought. Set it up early and never get used to having that money. If they don't have something like that or there is a waiting period, then setup an account with someone like ING and setup an automatic transfer of some amount of money per pay period that you consider already gone. Online/mobile banking makes your financial life so much easier than it used to be and the reporting services available will really help you control your budget.