First it is depending on your country mega stock [means the stock which shows you conditions of market in india it is nifty 50] you have to invest in stock when the mega stocks is very low because it will go up some day if you are successful to invest at proper time then don't worry it will be good . Invest in economic crisis , during the crisis almost every company stock are low and they will go up and it will increase your profits and it will help companies to get some money to maintain there businesses in economic crisis.