When to buy?
You can buy shares any time. Look for good companies with shares at attractive valuation. Best proven method of investing in shares is invest regularly and periodically. Invest a portion of your savings in to shares every month, don’t bother about index level. It may go up and down. But a regular investor can average the cost and earn a decent return in the long run.
When to Sell?
Sell when your investment objectives reach. If you bought shares of good companies, normally you don’t have to sell your shares until your investment objectives reach. When you start investing in shares, you should have a long term goal such as marriage after 3-5 years, buying or building a home after 5-10 year, children’s higher education after 15-20 years, children’s marriage after 15-25 years, or your retirement. Sell your shares only when time of your investment goal arrive. Don’t be panic to sell shares when the overall market fall or don’t tempt to sell when share market soars. But just have an eye on news about the industry and the company you invested in. If there is a real reason to believe that it is not worth continue to hold due to a concern about the prospect of company or the industry, then don’t hold but sell.