"With luck," cracks Older Women's League (OWL) president Tish Sommers, "every young woman will some day be an old one."

To prepare for that time, she and OWL executive director Shirley Sandage offer this advice to young women:

* Examine the details of pension plans--yours or your husband's--for which you think you'll be eligible. Most private companies require 10 years of continuous service--beginning at age 25--for employes to receive pension benefits. If you expect income from your husband's plan, find out if there's a survivor benefit. Under some plans, when the husband dies, the pension funds stop. Should the husband die before retirement age, the wife may never receive any funds.

* Plan now for retirement income. Look into IRA and Keogh accounts and other sources of financial support in later life.

* Consider what would happen to you, should your husband die or should you divorce. In some states, management of property goes automatically to the person who holds title. To find out how your state laws work, call the local Commission on Women. Some health-insurance policies are "non-convertible"--which means the wife may be unable to get coverage after divorce if the policy is in her husband's name.

* Recognize that, chances are, you're going to live the last part of your life without a spouse. Begin considering--at least mentally--your alternatives for housing, income and companionship.

* Start taking care of your health now. Older women live longer, but are prone to more chronic illnesses, such as osteoporosis. Exercise, diet and stress reduction in youth can make a big health difference in old age.

* Pay attention to legislation affecting the elderly. The bill you ignore today could make a difference tomorrow.