Thinking of buying some Canadian mining stock? Picking up a franchise in Daniel Boone Fried Chicken, Inc.? How about making a little spare change breeding chinchillas? Or would you prefer to play it safe and invest your hard-earned dollars in series E bonds? Don't do it. . . . The 'no risk' once-in-a-lifetime 'business opportunities' knock repeatedly and some are beyond the slow-moving S.E.C. and the myopic Better Business Bureau. Even Uncle Sam with the complicity of the corner savings bank discriminates against his small investors and today's Shylock probably has an advanced degree in ""Seven Emotional Keys or Ways to Sell"" mink oil or Turific soap suds. Author Margolius (The Consumer's Guide to Better Buying, How to Make the Most of Your Money) has some further tips for the gullible and the greedy on rationalized investment plans, including charts and tables of compound interest rates, broker's tips, the pros and cons of mutual funds, tax-exempt securities, mortgages, trust funds and the market records of most popular growth stocks. And in case all the good advice is lost on you (P. T. Barnum: ""there's one born every minute""), Margolius includes a list of private and federal agencies where you can seek redress and commiseration.