Deborah Schneider spent far more time researching the $15,000 car she once bought than she did on a slightly larger purchase -- her $90,000 law degree.

"Years later, I realized how common that is," says Schneider, who authored Should You Really Be a Lawyer? with Gary Belsky and produces its accompanying Web site. "Each year, many college students spend more time planning their next spring break than their postcollege career, even though they'll spend a lot more time on the job than on vacation."

Consider Your Choice Challenges

Blame what Schneider and Belsky call choice challenges, or mental traps that practically everyone falls into at times, especially when making major career decisions. Three of the most common choice challenges you'll face as a college student are:

• The Herd Mentality: The tendency to do what everyone else seems to be doing. Example: "All my friends are majoring in business, so I will too."

• Anchoring: Attaching great importance to something that may have little or no bearing on your best interests. Example: "My parents have always wanted me to be a lawyer."

• Decision Paralysis: Becoming so overwhelmed with choices that you can't decide, or you decide not to decide. Example: "I don't know what I want to do, so I'll just go to graduate school to keep my options open."

Schneider and Belsky also write about 10 more choice challenges:

• The Confirmation Bias: The tendency to seek information that confirms your existing knowledge and shut out what contradicts it. Example: Talking to friends and family who say a career in medicine sounds great instead of asking actual doctors who might suggest otherwise.

• Ignoring the Base Rate: Disregarding the odds of success within a situation. Example: Assuming you'll land a job in professional sports after you finish college, even though relatively few new grads actually pull that off.

• The Information Cascade: Being influenced by repeated exposure to certain facts. Example: "I'd better go to graduate school to wait out this bad job market."

• Mental Accounting: Treating money differently depending on its source and your use for it. Example: "My family will pay for my degree if I major in finance, so I might as well be a finance major even though my heart's not in it."

• Overconfidence: Overestimating your abilities, skills or knowledge. Example: "I really don't know what I'll do with a master's degree, but I'll figure it out by the time I'm done with grad school."

• Regret Aversion: Making decisions to avoid feeling bad in the future. Example: "I'm going to stick with my biology major, because if I change to something else, I might be sorry later."

• Rules of Thumb: Mental shortcuts to make choices easier. Example: "I better not major in art, because you can't get a job with that degree."

• The Status Quo Bias: Resisting change in favor of the familiar. Example: "I don't really like my current internship, but at least I know what to expect from it."

• The Endowment Effect: Putting higher value on something you have than you would if someone else had it. Example: "I hate my math major, but I'm doing so well in it that it makes no sense to switch to psychology."

• The Sunk Cost Fallacy: Overemphasizing the money, time, psychological energy or other resources you've invested. Example: "I can't throw away my $75,000 MBA and become a teacher."

Avoid the Career Traps

Are you making any of these miscalculations? If so, work on identifying and asking better questions about your future career, and take time to research careers using a variety of sources, says Schneider. The counselors at your school's career center can help.

"If they don't, investing in a good career book or a career counselor in private practice is worth the time and money," Schneider stresses -- especially when your future happiness is at stake.