First the bad news. College costs have taken their biggest inflationary jump ever, according to college financing expert Robert Leider.

For the 1979/1980 school year, he says, the average expenses for a resident student at a four-year private college will total $5,733 and at a four-year public college, $3,567.

Now the good news. Nearly $15 billion in grants and scholarships and $5.25 billion in loans and work programs are available to help pay the nation's annual $33 billion tuition bill.

However, says Leider, "students are generally too busy shouldering their academic loads to have time for a thorough study of the process. Most parents know something about the GI Bill, but that's it."

Leider, of Alexandria, has streamlined the financial-aid maze into the top-selling 31-page pamphlet, "Don't Miss Out: The Ambitious Student's Guide to Scholarships and Loans."

"One of the biggest mistakes people make is not applying for financial aid because they think they're too wealthy," says Leider, citing the case of a daughter in a $50,000-a-year-income family who received aid.

"Another mistake is the feeling that assistance is limited to high-school kids," he says. "If you're 32, divorced and want to go back to school full time you have the same eligibility for aid."

A retired Army colonel, Leider stumbled into the publishing business four years ago when his daughter was applying for college.

"She was not getting much information about financial aid," recalls Leider.

When Leider began researching financial aid he discovered his income was too high to qualify for standard aid. But his daughter eased the tuition burden at Amherst College by winning a $10,000 National Football League college scholarship for her essay on "The Contribution of Football to American History."

Students and parents often fall into the trap of filling out a financial-assistance or "need-analysis" form, sending it to the college and then sitting back and waiting for the decision.

The decision can be a shock," says Leider. "In most instances, the family's contribution will have been judged to be far greater than the parents expected or thought they could afford.

"There is panic in the household and no time to select an alternative strategy in an orderly manner. The outcome is often a college choice that does not serve the youngster's best interests."

Starting early is one way to avoid this. "The (high school) junior year is the best time to start becoming familiar with the system," says Leider.

To avoid "nasty surprises," he advises measuring the family contribution against the college cost at the same time requests for catalogues are sent out.

He also suggests sending for the college's financial aid package, which should list scholarships, grants, loans and employment programs available. Expensive schools are usually heavily endowed and may be in a better position to offer a financial-aid package than lower-cost schools.

"Apply for financial aid as early as possible," says Leider, who updates his book 8 to 10 times each year. "Schools can often meet the needs of the first applicants, and then run out of assistance money for late applicants."

Leider also suggests checking to see if the college of your choice offers any of these resource opportunities:

Academic scholarships. Some colleges offer honor or merit scholarships regardless of income. If you have accumulated a B average or higher, stand in the top 25 percent of your class and have ACT scores of 20 or more, or a combined SAT of 1,000 or more you may be eligible.

Acceleration. Shortening your stay in college can reduce costs. Some schools let you take college courses for credit while in high school. You may get college credit through programs such as advanced-placement or college-level examinations.

Cooperative education. Schools with cooperative-education programs incorprate jobs as part of the curriculum, alternating work and classroom periods.

Special programs. Ask about special financial-assistance plans, including scholarships and loan programs for middle-income families, deferred repayment (repaying costs over 25 or 35 years), guaranteed cost plan (paying four years' tuition in advance to avoid future increases) and parent-loan programs (loans to families earning $15,000 to $75,000 per year at 8 to 8.5 percent interest). "Don't Miss Out" is available in school and public libraries. It can be purchased for $2.25 by writing Octameron Associates, P.O. Box 3437, Alexandria, Va. 22302.