Korean students on school

7. 'I have credit card debt but want to open a new card to get 25,000 airline miles.'

As tempting as the offer may be, you shouldn't take advantage of it, says Heather Lovett, director of public relations for DealNews. "If you are carrying credit card debt, your only goal should be paying off that extremely expensive debt," she said.

Most credit cards that offer travel rewards require that you spend a minimum amount to accrue points or free miles. "Those free miles will suddenly be very expensive when the $3,000 minimum spend costs you 22 percent in interest per year," Lovett said. "And if you fall further behind, your credit score will drop, making any future borrowing more expensive."

8. 'I don't need to worry about retirement savings because I expect to get an inheritance.'

It's unwise to assume that just because your parents are retired and seem to be doing well, you will inherit a significant sum, said Michael Fuhr, a certified financial planner with SageVest Wealth Management. Your parents may need a large portion of their assets for health-related expenses, especially if they require nursing home care and don't have long-term care insurance to cover it, he said. If there are multiple siblings, a potential inheritance may be reduced further.

Or your parents might decide to spend their hard-earned money on themselves during retirement. "If you don't know what their plan is, then you can't assume it includes you in a significant way," Fuhr said. It's always best to be disciplined and save for your own retirement.