(MONEY Magazine) – Your year-end issue has advice from professional investment managers. I'd like to offer mine as a small investor who ''goes it alone.'' When I bought Compaq at $15.25, I knew I had made a good investment. I sold at 352% profit. When I bought Cytogen at $4.25, I felt the same, especially after a 400% return. Also, with Vector Aeromotive (500%) and Sony (400%). In 1989, I selected Chile and Argentina as countries ripe for investment. Next? The Baltic republics. My stock-picking strategy includes the following: -- The stock must trade on the New York or American exchange or over the counter at about $10 a share. -- The product must be one that I know from personal experience is superior to competitor products, or I must have knowledge that management is exceptional. -- The stock price must be at least five times less than a competitor's stock. After profit taking, I divide the proceeds into strip-zeros and reinvest in another appropriately selected growth stock. Daniel M. Zibman Philadelphia