Why and how to invest--for timid (or untutored) souls who may be shortchanging their own financial futures. At the outset, Nelson, a Merrill Lynch V.P., makes a conventional case for active assets management--citing, for one thing, a 60 percent devaluation in the dollar since 1960. More telling perhaps is his observation, late on, that ""over $700 billion is sleeping in low-yield passbook savings accounts,"" while only $70 billion has been put into lucrative money-market funds. Then he weighs, in detail, the basic alternatives: funds, plus corporate bonds, tax-exempt municipal issues, US Treasury obligations, and common stocks. He also evaluates such often-overlooked commitments as federal agency debt, unit trusts (whose holdings are not traded), tax-deferred annuities, tax shelters, and equities with dividends partially or wholly beyond IRS reach. (Conspicuous by their absence are collectibles, commodities, exchange-listed options, foreign currencies, precious metals, and other speculative vehicles.) Nelson is careful to point out drawbacks as well as advantages--reminding readers, for instance, that payouts on moneymarket funds can go down as well as up, depending on credit conditions. And investments, unlike bank deposits, are not insured against loss. Included along with a range of smart-money recommendations (e.g., creative use of the Uniform Gift to Minors Act) are: precise instructions on how to handle securities transactions; general guidelines for hiring or firing a broker; and a lengthy glossary that translates Wall Street lingo to language. The dubious title apart, one of the better advocacy primers for investment tyros.