NEW YORK ( MainStreet) — Figuring out the myriad reasons why lenders deny credit card applications can be complicated, but consumers can boost their likelihood of approval.

The process to approve consumers for credit cards varies among lenders, each having its own criteria that people must pass.

"Consumers should do their research in advance and only apply for the cards that are likely to grant the credit they seek," said Gail Cunningham, spokesperson for the National Foundation for Credit Counseling. "Credit card companies want to extend credit, but only to people who represent a low risk for default as defined by their business model."

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Consumers can easily improve their credit and position themselves to increase the likelihood of credit being extended.

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Some people, especially Millenials who are working at their first job, simply lack having enough existing credit . Lenders prefer being able to review a track record of how a person has managed credit in the past, she said. A thin or nonexistent credit file can give a conservative lender reason to deny.

This can be easily remedied by building credit judiciously such as starting with a secured credit card , but consumers should confirm in advance that the issuer reports activity to the credit bureaus, she said. Another option is to consider becoming an authorized user on another person's card as the activity of the primary cardholder as well as the authorized user is reported to the bureaus.

For renters who have little or no credit or are simply looking to build their credit profile, they can opt-in to have their rent payments reported, said Jeff Golding, CEO of WilliamPaid, a Chicago-based company which allows people to build credit through paying their rent online for free.

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A few companies such as WilliamPaid allow people to report their rental payments to one or two of the credit bureaus.

"It's typically a renter's largest monthly obligation, and it must be done every month, so take advantage of adding a positive trade-line to your credit report," he said. "The addition of positive rental payment data in Experian credit reports can be a tremendous benefit to anyone who rents, especially non-credit-active, cash-based consumers. We have helped a lot of people go from not having enough credit history to generate a score to being approved for a mortgage."

Another reason credit card applications are denied is when your pay history is poor, said Cunningham. The highest weighted element in the scoring model is how a person repays his or her debt obligations. A history of skipped or late payments can be a knock-out punch when attempting to obtain new credit.