9 Things Every Twentysomething Needs To Know About Money

Before you can do anything — make investments, save for retirement, save for a vacation — you have to know how much you spend. You can do this the hard way, or you can use Mint. Its basic budget- and spending-tracking tools are free. The trick here is to figure out how much you spend in a typical month and then figure out how much you have to save.

Look at your subscriptions. Are you actually going to the gym that much? Do you really need Hulu Plus, Amazon Prime, and Netflix? And cable TV? Subscriptions work by masking their true annual (and longer) cost, so be sure you're only subscribing to stuff you really want or need.

This is the annoying part. You have student loans. Your paycheck is way smaller than you expected. (Taxes!) But it's really important: Even if you lose your job, you still have to pay rent and eat. So put aside some portion of your paycheck… Every. Single. Time. Ideally, you want to build up your savings so that you have enough to cover six months worth of expenses. Also, as your income increases, try to increase the amount you save.

Now this is more annoying than just setting aside part of your income for an emergency. You're saving for something that's not going to happen in, hopefully, a very long time. But the benefits to starting early are huge. If your employer offers a 401(k) plan, contribute as much as you possibly can, especially if there's an employer match, which is one of the best deals you can get. Also, if you can, start saving and investing early. Eventually you want to be contributing around 15% or 20% of your income to retirement savings.

Socrates may or may not have said, "I am the wisest man in Athens for I know nothing," but he would have been an excellent investor. When you're choosing a mutual fund or funds for your 401(k) or other retirement savings, pay attention to the fees, especially the "gross expense ratio," which is an all-measure of the costs of running the fund. You're probably not a great judge of which mutual fund strategies will work in the future, but it's easy to see which are the cheapest.

If you have a steady income, going into some credit card debt isn't the worst thing in the world for one-off expenses. But using your credit card — assuming you don't pay the full balance every month — on routine expenses is a recipe for carrying a larger and larger balance and then making interest payments that are always higher than you expect, leaving you paying off your balance for longer than you think.

If you're stretching on your credit card, try to find the lowest interest rate and annual fee. But if you're paying off the full balance and spending a high amount, actually look around for which card has the best rewards program (Mint has a great guide). If you're a responsible credit card user and aren't getting the best rewards, you're just leaving money on the table.

Big financial problems happen when people face huge expenses from something like a health emergency or their income suddenly dries up because they lose their job. Thanks to Obamacare, in 2014, the health cost problem will hopefully be solved. But until then, it's vital to insure yourself against low-risk, high-impact events. This means getting some kind of health insurance even if you're young and healthy and saving and don't think you're at risk of losing your job.

This is a little philosophical, but it's unlikely that buying another thing — a dress, pair of shoes, sunglasses, whatever — is going to make you that much happier for all the money you spend on it. But activities you do with people you like — day trips, going out to eat with your friends, concerts — will make you happy every time. And having good relationships is the best investment you can make.