it is hard to be accurate. You may not believe even if I give you a number with one or two accounts. All I can tell is it is easy to make 10-15% year after year. 20-30% is not uncommon. An unmarried office worker lady in NY left $18 million by trading stock and donated to the city library when she past away about 10 years ago.
You do not need to overly diversify. Focus on a few good companies you understand. Find all information you can. 5-10 sotcks may be enough depending on how much money you have. There are hundred companies that give you return of 15-30% for the past 10-20-30 years.
Do not get too greedy and invest in what you understand. Do your own research (due deligence). It doesn't work very well to invest by only getting tips from your friends. You either sell the stocks at low point at panic when situation becomes bad, or too early when you make a little profit without truly knowing the company and its financial situation.
