Investing for the short termIt's fine to buy one share to get started, but avoid investing substantial quantities of money that you might need in the upcoming year
Playing it safeDon't put all of your money in low risk, low yield equities if you're young. You have years to ride out the market downturns and reap the enormous benefits.
making a dangerous moveOn the other hand, refrain from investing all of your money in risky businesses, especially overvalued equities that lack viable business strategies or capable management