10 steps to becoming an expert investor

Be strict with your stop loss. It means when you are losing money, cut your losses and get out of the market. Similarly, if you are on a winning spree, setting a proper stop loss will protect your profits when the stock markets start going down.
Learn whenever you suffer a loss. We lose money in the market due to our mistakes. Find out where you went wrong and ensure you don't repeat it.
Avoid greed. It is easy to put money in a dud stock just because it is going up. You might be in a hurry to whip up some quick money for a down payment for your home loan or the down-payment for a new car hitting the roads. However, be wise and remember this price rise is due to market manipulation rather than any genuine change in the company's financial situation. Also, understand that to reap the best benefits you need to stay invested in a good stock for a long term.
Avoid leveraging. Many people borrow heavily from others in order to maximize their profits. Though this may work in certain instances, it can also cause massive losses if the market cycle turns. This can lead to financial as well as mental stress, and can lead to destruction of family lives as well as suicides in certain instances.
Don't act if you are not sure which way the stock markets will move. In such instances, it is better to be a passive onlooker instead of participating in the market action.
Read a lot. There are many good books on investing available on the subject. Always keep on updating your knowledge. Also follow thoughts and opinions given by respected investors like Warren Buffet, Rakesh Jhunjhunwala, etc. It will expand your knowledge and help you tackle any market situation comfortably.

Limit the number of stocks. Ensure your holding comprises not more than 20 stocks. Also ensure these stocks are from companies operating in different sectors to protect your portfolio from losing its value.
Don't use various investment strategies. If you are comfortable with buy and hold strategy, use the same one for all your stocks. Otherwise you might be confused with which strategy actually helps you make money.
Remain patient and disciplined, whatever the market condition. If the markets are crashing don't get out of the market, but wait for the market to go up. Also don't continue to invest in the stock simply because it is going up.
Choose stocks as per your risk profile instead of the returns they generate. If you are not comfortable with the high volatility of the small- and mid-caps, don't invest in them.