A survey by TIAA-CREF found that less than one-fourth of Americans have an IRA account, and less than half of those who do take advantage of the full contribution limit. The same study also found that many people, especially younger adults, are completely unaware of what an IRA account really is or how it works.

There are two main types of IRAs, traditional and Roth, and although they have some significant differences -- mainly in their tax treatment -- there are a few universal rules that apply to any IRA. Here are five big ones that will greatly improve your understanding and help you make solid decisions about your own financial future.

1. You can get started with a dollar
Most major brokerages do not demand a minimum amount of money to open a new IRA, whereas regular brokerage accounts can require an initial deposit of $2,000 or more. You can literally open an IRA with a dollar.

While this isn't very practical, the point here is that you can't use the "I don't have enough money to invest" excuse. I opened my first IRA with $50 and bought two shares of Intel. You'd be amazed how $50 here and there can accumulate over time.

2. Maxing out your IRA
Both types of IRAs have the same maximum annual contribution, which is the lesser of $5,500 or 100% of your earned income. So if you are in school and earn $3,000 per year in a part-time job, that's the maximum you can put in an IRA.

If you're age 50 or older, you can make an additional "catch-up" contribution of $1,000 for a total of $6,500. This is intended to help those who may have waited a little longer than they should have to started investing in an IRA.

It is important to note that the limit applies to all of your IRA accounts combined. For example, you can contribute $2,000 into a traditional IRA and $3,500 into a Roth, but not $5,500 into each.

3. The tax benefits are excellent, if you qualify
While everyone can contribute to an IRA in one way or another, to qualify for the best tax treatment, your income cannot exceed certain limits.

To make a full contribution to a Roth IRA, you must earn less than $114,000 per year in 2014 as a single filer or $181,000 if you're married filing jointly. Eligibility to contribute phases out entirely for those with incomes above $129,000, or $191,000 for married taxpayers.

Unlike the Roth IRA, anyone can contribute to a traditional IRA and let their investments grow tax-deferred. However, if you are covered by a retirement plan at work, your modified adjusted gross income must be below $60,000 if you're single or $96,000 if you're married in order to qualify for a full deduction, and the ability to deduct contributions phases out entirely above incomes of $70,000 for singles and $116,000 for married taxpayers. If only one spouse is covered at work, the limit rises to $173,000. If you are not covered, there is no income limit to deduct your contributions.

4. How to withdraw your money
Generally, you can't withdraw your money penalty-free from a traditional IRA until you are 59 and a half years old without incurring a 10% early-withdrawal penalty. There are, however, a few exceptions. For instance, if you're purchasing your first home, you may be able to withdraw money without penalty to help with the down payment. Education expenses or medical expenses may also qualify. Also, if you become disabled or deceased, your money can be withdrawn without penalty.

Meanwhile, a Roth IRA allows you to withdraw contributions (but not gains) at any time, and for any reason, without penalty. You also are not required to withdraw money from a Roth IRA at all if you don't need it, which makes the Roth a good choice if you might just leave your money for your heirs to inherit. Traditional IRAs, on the other hand, require you to begin taking distributions by the time you reach 70 and a half years of age.

5. What you can invest in
An IRA is somewhat similar to a 401(k) plan in that your investments grow tax-free. However, one major difference is the types of investments you can make.

With a 401(k), your plan administrator generally gives you a selection of funds to choose from. In an IRA, you are free to invest in stocks, bonds, mutual funds, CDs, and ETFs. While many IRA investors still choose to keep their portfolio relatively simple by investing in index funds and other low-maintenance investments, an IRA puts you in control of your own retirement money in a way most 401(k) plans don't.