When Katherine Cohen was studying for her Ph.D. in Latin American literature at Yale University, she worked in the admissions office reading applications. "I've seen some weird ones," says Cohen, 34. "One student drew little drawings of butterflies, flowers and rainbows over the essay. It was so immature! Another [essay] was about this young woman who was raped by her uncle. She needed to get help—but not from the admissions board at Yale."

Cohen decided to offer guidance of a different sort and in 1998 hung out her shingle to become one of now roughly 4,000 private college-admissions counselors. That figure has doubled in the past five years as higher numbers of applicants have made college more competitive than ever. Based at her Manhattan company Ivy Wise, Cohen offers a range of services, from reviewing her clients' applications to brainstorming essay ideas, holding mock interviews and helping to plan course loads and college visits. Now readers can soak up some of her professional wisdom in her new book The Truth About Getting In. Cohen, who draws clients from as far away as Hong Kong, says 75 percent of her students get into their first-or second-choice school. "Katherine is young, and she relates to students," says Andrea Stark, whose daughter Ashley is a sophomore at Brown. "You need every advantage."

Cohen, who is single and lives in New York City, shared some tips with PEOPLE contributor Eve Heyn.

Is it really so crucial to get into a top college? Plenty of CEOs didn't go to Harvard or Yale.

You can get a great education at a middle-level school, and there are studies that show there's not necessarily a correlation between going to a selective school and success in life. What's important is getting into the best school for you—where you'll be the most successful and happy. But even moderately selective schools are harder to get into nowadays.

Why?

Because we're in a post-baby-boom, the applicant pool is growing by tens of thousands every year. As the competition gets fiercer, applicants push harder to build impressive résumés. To stand out from the crowd, you need to have a plan.

When should this planning begin?

The summer before ninth grade. You should have a four-year plan for courses, which should get increasingly challenging, for extracurricular activities and summer experiences, and a standardized-tests schedule.

Can't students take the summer off?

Absolutely not. Take two weeks of downtime with your family. But don't spend the whole vacation working on your tan. Take a summer abroad, a program where you're studying a second language in depth. Bolster your curriculum at summer school. Work at a job or internship.

What are the most important factors a college looks for?

Test scores are not as important as everybody thinks. A perfect 1600 isn't going to guarantee you admission anywhere. Colleges are much more concerned with how you perform in class over four years instead of over three hours on a Saturday morning. The most selective schools are looking for high grades, but they'd rather see you in an honors class getting a B-plus than a regular class getting an A-plus. They want to know you're challenging yourself. They're also looking for consistency and commitment. So if you're considering Spanish in ninth grade, keep taking it in 10th, 11th and 12th.

What's second after academics?

Character. At the top schools 80 percent of applicants can do the work. So the question becomes: Who are we inviting to our campus? They want a responsible, nice kid who's going to participate—not an arrogant loner.

How about extracurricular activities?

They're important, because they show your personal qualities. But don't devote a half-hour a week to 20 different clubs. Do a few things you love and do them wholeheartedly. Also, colleges love work experience. Almost any job will do. You don't want to appear spoiled or lazy.

What's the best approach for the essay?

Tell a story, one that's small in scope but speaks volumes about you. It may just be a day in your life, but it should be full of details that let the reader get a sense of who you are.

How many colleges should a student apply to?

From six to eight. Two "reach schools" you dream of, even if your chances are slim. Three or four schools in the "target range," meaning your profile is similar to that of a typical incoming freshman. And one or two "safety schools."

Aren't our kids already too stressed out? Can they have any fun with this process?

Parents should encourage kids to do things they love, but don't force them into activities. If your child is into sports, you might suggest he or she start a sports column in the school paper. But don't go overboard. I've heard of parents worrying about college in fourth grade, which is way too early. Kids need to be kids too.