Some financial decisions are easy. You know, for example, that you should pay your rent instead of blowing the money on an impulse trip to Cancun.

But some financial choices are a tougher call. For example, you know you should build up your savings and it's also important to pay off your debt. But which one trumps the other? When you're faced with a choice between two worthy options, how do you know which path makes the most financial sense?

We've put together a cheat sheet of answers to five common dilemmas and arm you with the tools to help you make the best choices for your situation.

Q. Should I save/invest or pay off debt?

A. Evaluate which option will give you a bigger return on your money. (Use this calculator to help crunch the numbers.)

For example, if you have credit card debt charging 18% interest, paying it off is like receiving an 18% return on your investment. It's pretty hard to find that kind of payoff in the stock market. On average, stocks have historically returned about 10% annually. On the other hand, if you have student loans charging 3% interest, paying ahead on that debt doesn't make much sense. You can generally get a higher return elsewhere. In that case, make your regular monthly payments and set aside any extra money in higher yielding savings or investment accounts.

Of course, despite all the number crunching, there's something to be said for the feeling of being debt-free. If investing makes more sense on paper for your situation, but paying off your obligations will bring you greater peace of mind, go for it. A good financial decision is one that helps you feel in control of your money, not the other way around.

Q. Should I invest in a 401(k) or Roth IRA?

A. Generally, it's best to invest in a 401(k) up to the employer's match -- otherwise you'd be passing up free money. But if your employer doesn't offer a matching contribution, go with a Roth IRA first.

You can invest up to $4,000 in a Roth IRA this year. If you want to save more, you can contribute to your 401(k) after you fully fund your Roth. You contribute after-tax dollars to a Roth, so it won't reduce your taxable income like 401(k) contributions will, but you can withdraw the earnings tax-free once you turn 59½.

This is important if you expect to be in a higher tax bracket when you retire. And there are other benefits with a Roth that you won't get in your 401(k), such as no mandatory withdrawals and no penalties if you need to withdraw your principal early (for more, see An IRA Owner's Manual).

If you make too much money to qualify for Roth contributions ($110,000 for singles or $160,000 for joint filers), max out your 401(k) first, then invest in a traditional IRA.

But before you invest in any retirement plan, make sure you have three to six months worth of living expenses saved in an emergency fund, and you've paid off your high-interest debt (see above).

Q. Should I rent or buy a house?

A. There's no one-size-fits-all answer to this quandary. To come to an answer that fits your situation, ask yourself these four questions:

• Can I afford the monthly payment?

• Do I have enough savings for a sizable down payment? You generally need at least 20% of the purchase price to avoid paying private mortgage insurance. Low-down and no-down financing can help, but you'll still need enough for closing costs, origination fees, and other expenses -- and you'll probably pay a higher interest rate.

• Can I afford the extra costs that come with owning a home, such as insurance, taxes, maintenance, repairs and furniture?

• Do I plan to stay put for at least five to seven years in order to recoup my initial costs?

Use this calculator to see whether you're better off renting or buying in your situation.

Many younger people find that renting is quite a bargain. In fact, the national gap between the costs of renting and buying is the widest it's been in more than a decade, according to Torto Wheaton Research. That means you may actually save money by renting, at least in the short-term. But that doesn't mean you should resign yourself to a lifetime of renting. Rather than overextend your budget to buy -- especially in today's overheated market -- you can rent comfortably within your means and save your money for the perfect opportunity when it comes along. Check out these four places to house your cash until you're ready to buy.

If your situation points you toward home ownership, our Home Buyer's Survival Kit will guide you through the process step by step.

Q. Should I save my emergency cash in a bank account, CD, money-market fund or under my mattress?

A. Nix the mattress. The rule of thumb is to save three to six months' worth of living expenses in case of a financial emergency, such as job loss or unexpected medical bills. You'll want to put the money someplace safe and accessible, but you don't want it to sit in a standard bank account earning next to nothing. Go with a high-yielding money-market account, such as Emigrant Direct (currently yielding 3.5%) or ING Direct (3.3%). (Shop for other high rates.) These FDIC-insured offerings link to your checking account at your bank, and you simply transfer the money online. Transfers take between two to four business days to clear.

You can probably do without a traditional money-market mutual fund. Some of the highest-yielding money market funds currently yield less than 2%. And although they are generally considered safe investments, your money is not insured. However, a money-market fund with check-writing privileges allows you to write a draft any time without waiting for an online money transfer to go through.

CDs are safe, and they earn good yields, but they don't satisfy the accessibility requirement. Your money is tied up for the term of the CD, and you'll have to pay a penalty to cash out early. By definition, an emergency is something you do not anticipate, so it's best to keep your money unshackled.

Q. Should I take job A or job B?

A. When choosing a career path, your first instinct may be to go with the one that pays the highest salary. After all, you've got bills to pay. While certainly important, your paycheck isn't everything. To evaluate two viable job offers, you need to look at the entire picture. For help, check out our Job Assessor calculator. It asks you to zero in on the criteria you find most important, and then see how your two job prospects measure up to your preferences.

Areas you should evaluate include benefits packages, commute times, opportunities for advancement, the work environments, levels of responsibility and job security. And it sounds cliché, but envision where you want to be in ten years. Would one job take you down a different career path than the other?

The same evaluation process works for deciding whether to stay at your current job or try something new. The idea of stepping outside your comfort zone can be daunting, especially if you're leaving your first real job out of college. Breaking the decision down into objective categories helps take some of the emotion out of the process. Take an honest look at the criteria above, and include job satisfaction, stress level and office politics into your equation.

If you're considering a switch to a new field entirely, take our online self assessment to see if you're ready for a career change and get advice on how to smooth the transition. Our Am I Ready to Change Careers? quiz will help you evaluate whether a switch is worth the professional and personal ramifications.

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