What is “the best insurable class”, and can I qualify for it?

For most of the insurance companies, to qualify for the best insurable class, a person should have no personal history of disease or impairment that would affect mortality; normal (or well-controlled with medications) reading of blood pressure and cholesterol; no cardiovascular disease or cancer in either parent or siblings before age 60; good driving history; no use of tobacco; no substance or alcohol abuse. There may be other factors.