MISSISSIPPI STATE -- "Putting it on plastic" has become second nature to many American buyers, but not reading the fine print has gotten a lot of them in trouble.

Dr. Beverly Howell, family economics specialist with Mississippi State University's Extension Service, said consumers are responsible for the credit choices they make and should always be cautious with their decisions.

"The responsibility lies with the consumer to use credit to their best advantage," Howell said. "Sometimes that means not using credit cards at all."

The credit card market is very competitive as companies try to win new customers. Two common offers can be useful to consumers, but can also get them in trouble if they're not careful. Many companies are offering low rates of 4 to 6 percent interest on credit cards. Others offer convenience checks that can provide cash from the credit card.

Offers of low credit card interest rates are time-limited, and balances transferred to these cards are charged interest at a higher rate after a fixed time. Even though the rates increase, Howell said these offers can be useful if people pay off the amount before the higher rate takes effect.

"If you do transfer a balance to a new card, you have to make a decision to close out the other card," Howell said. "You don't want a lot of open cards on your credit report, even if there is no balance riding on them."

Contact the company issuing the credit card to close the account, and ask them to indicate the account was closed by the consumer. Instead of transferring an existing balance to a new card, Howell recommended requesting a lower rate from the current credit card company.

"This allows you to get a lower rate, and the company keeps a customer," Howell said.

Another popular marketing tactic today for credit card companies is offering convenience checks. When using these checks, consider the interest rate that will be charged, any issue fees and whether there will be a transaction fee, which can range from $10 to 4 percent of the amount.

These checks usually do not offer an interest-free grace period, and many times they are treated as cash advances and charged at a higher interest rate. Howell said a typical effective annual percentage rate on convenience checks is 20 to 30 percent.

Credit blocking is a practice many companies use when accepting reservations using credit cards. This protects the company, but can affect a consumer's spending.

"Many times when you reserve a hotel room or rental car, the company puts a hold on your credit card for the amount of the service, plus a little more to cover themselves," Howell said. "This is done to ensure money will be available on the credit card to cover the expense."

Credit blocking can cause trouble if the card is close to the limit and the user tries to make other purchases.

"To limit problems, ask how long the credit line will be blocked when you make credit card reservations. Pay with the card you made the reservations with, as using another card or cash can mean the block may stay on the card for 10 to 15 days," Howell said. "Check with the credit card company later to make sure the block was removed."

Using credit cards is a very convenient, popular way to make purchases in today's economy. Wise consumers read the credit card contract before agreeing to the service and understand the fees, interest rates and how the interest is calculated before accepting the card. They also have a plan for paying off the balance in a timely manner.

"Paying only minimum payments can result in paying a great deal of interest and having a very lengthy repayment process," Howell said. "It is important to see how much of that minimum payment goes only to interest and how much is applied to the principal. Pay more than the minimum or it will be a long time and many dollars later before you pay it off."