Forbes Mitch Tuchman advises stock market beginners understand these simple ideas: “1. Index funds and ETFs represent your best opportunity to diversify and cut risk while staying investing in markets high or low. 2. A well-designed investment portfolio will neither zoom higher with equities nor crash to earth with corrections. Rather, you will sell off as stocks rise and reinvest in them when prices fall, using new cash, dividends and interest inflows.”