Image:  Stack of Credit Cards © Fuse, Getty Images

Are you too plastic for your own financial good? Although there is no magic number of credit cards that should be in your wallet, some key questions can help you determine whether you're charging around town with more plastic than you need.

According to recent data from Experian, the average U.S. consumer has three open and active credit cards. Whether that is too many, too few or just enough for you is really a question of how you use and manage your accounts.

If you have the tendency to spend more than you earn, you might need fewer than three credit cards -- and maybe none at all, says Harrison Lazarus, a financial consultant and founder of Harrison Lazarus Advisors. On the other hand, if you spend well within your means, more credit cards could be good for you. "You will be able to access money when you need it, obtain fringe benefits like rebates and mileage, and improve your credit score," Lazarus says.

If you are unsure (or in denial) about your spending habits and general attitude toward credit, here are some warning signs you have more credit cards than you can handle:

1. You pull your annual credit report and find open credit cards you had forgotten about. Do you open a store credit card every time you hear the words, "save an additional 10% if you open an account today"? Do you mail back credit card applications in exchange for offers of bonus miles? If so, chances are you have credit cards lying around that you have not used since the day you signed up.

Rod Griffin, the director of public education at Experian, says open accounts that you have neglected could increase your risk of identity theft. Cards that are left idle could be stolen and used to make charges long before you notice that they're gone.

If you have unused credit cards that you don't want to close just yet (more on that in a moment), Griffin says it's best to lock them away or keep in a safe deposit box in your bank.

2. You are not paying your credit card bills on time. You know you have too many credit cards when you start having bill payment issues. If you carry 10 credit cards, for example, and you use all of them, you have 10 monthly statements to deal with each month. "Having too many credit cards can lead to the lack of time and focus to ensure proper credit card management," says Kimberly Howard, a certified financial planner and owner of KJH Financial Services.

Every credit card requires a payment date, and each one could be different. Payment juggling could lead to missed or late payments, Howard says, which could ding your credit scores.

Even just one credit card might already be too many for you. "The total balance on all cards compared to the total credit limit on those cards is called the utilization rate," Griffin says. "A high utilization rate, whether you have one card or many, is a strong indicator of credit risk and will significantly impact credit scores."

3. Your credit scores have been dropping steadily. Several factors influence your credit scores, including your previous payment performance, your total outstanding debt and how long your credit accounts have been open.

Inquiries and new accounts can also adversely affect your scores. Every time you apply for a credit card, an inquiry is added to your report. This pushes down your credit scores a little. "An inquiry is viewed unfavorably because it means you are shopping for credit," Lazarus says.

To find out if the number of credit cards you own is a reason for your low credit scores, pull your credit report and look at the risk factors. If "too many revolving accounts" is listed, it might be a good idea to forgo future card offers and think about closing some already-open accounts.

4. You are having a difficult time getting a loan. Having too many credit cards could be among the reasons if you are denied a mortgage or car loan. Howard says loan officers nowadays frown on borrowers carrying more than five credit cards.

Even if you maintain zero balances on a handful of open cards, you can be considered a credit risk. "The loan officer realizes that you could use all of your credit cards after the loan is approved, and that will affect your ability to repay the loan," Howard says.

Click here to become a fan of MSN Money on Facebook

High credit scores alone should help prove you are worthy of loan approval, but Howard says that's not the case now. Since 2008, loan officers have been far more careful in approving loans, she says. "They are favoring mostly those with a limited number of credit cards, in addition to having a high credit score."

5. You are saving less than 10% of your gross income. If you look at your savings and you're not comfortable with what you see, it could be that you are spending (and charging) more than you can afford. Ideally, Lazarus says, you should be saving 10% or more of your gross income.

For example, if you earn $3,000 every two weeks (taking home $2,300 after taxes and other deductions), you should be able to save at least $300 every two weeks.

If that goal is too hard to achieve, fewer credit cards or none at all might be the way to go. "Less or no credit is better, because you will avoid overspending, underpaying, incurring excessive interest and reducing your credit score," Lazarus says.

Next steps: If, after reading this, you are convinced you have too many credit cards, should you immediately start closing accounts? And how do you know which cards to keep?

If you are looking to cut the number of credit cards you own, Howard says the first ones to go should be store credit cards, specifically those not carrying a MasterCard, Visa or American Express logo.

"Store credit cards are easily given to individuals with low creditworthiness," Howard says. "Once you have MasterCard, Visa or American Express, you need to start thinking about closing those store cards, because they will only hurt you during a loan application process."

Don't close all your cards at the same time, though. Every time you close a credit card account, your credit scores take a small hit. Howard's advice is to close them at six-month intervals, so your credit scores have time to recover before you cancel the next card.

Lazarus suggests hanging onto credit cards that have no annual fees and no overseas transaction fees and that offer rebates or cash-back rewards. He says the Chase Ultimate Cash Award MasterCard, CapitalOne Visa and American Express Blue cards are worth considering. "If you're going to use credit, you might as well make the most from it. In today's world, credit card issuers want your business and are willing to reward you for it."

If you find that the number of credit cards you have isn't causing you any problems, Experian's Griffin says you should be focusing on other financial issues that could be having a greater effect on your creditworthiness.

On the other hand, if you find it difficult to curb your spending or use of credit, you may want to check in with the National Foundation for Credit Counseling. Another useful resource is AdviceIQ, which lists financial advisers in your area.

Click here to become a fan of MSN Money on Facebook

More from TheStreet.com: