When investing in the stock market, you have to think long term and avoid the temptation to check your portfolio several times per day. All this will do is waste your time, stress you out, and increase the odds that you will make a big mistake and sell at the wrong time. Plan to set up automatic contributions to your investment so you can buy more investments no matter where you are.
Risk tolerance is a psychological trait that is genetically based, but positively influenced by education, income, and wealth (as these increase, risk tolerance appears to increase slightly) and negatively by age (as one gets older, risk tolerance decreases). Your risk tolerance is how you feel about risk and the degree of anxiety you feel when risk is present. In psychological terms, risk tolerance is defined as “the extent to which a person chooses to risk experiencing a less favorable outcome in the pursuit of a more favorable outcome.” In other words, would you risk $100 to win $1,000? Or $1,000 to win $1,000? All humans vary in their risk tolerance, and there is no “right” balance.
Alphabet (NASDAQ:GOOGL) (NASDAQ:GOOG) -- As a beginning investor, it wouldn't be surprising if you haven't heard the name Alphabet before, but it's likely you've heard of the company's main subsidiary, Google. As the dominant leader in internet search, Google has an effective duopoly on internet advertising, along with Facebook. Its massive stockpile of consumer data makes its ads extremely effective, and it's tough to imagine any competitor stealing any significant percentage of the market. And Google has the second-most-valuable brand name in the entire world, with an estimated value of more than $130 billion, according to Forbes. The fact that Google's brand has become synonymous with internet search and several other functions gives tremendous pricing power when it comes to selling ads.

Businesses you don't understand -- Here's a great rule of thumb that works for beginners and expert investors alike. If you can't clearly explain what a company does and how it makes money in a sentence or two, don't invest in it. There are literally thousands of publicly traded companies to choose from, and you should be able to find plenty of opportunities in easy-to-understand businesses.

Use limit orders: Always use limit orders rather than market orders, when trading penny stocks. The very act of buying or selling shares in a company that is thinly traded can result in the price moving due to your trade. In other words, your buy might cause the shares to temporarily and artificially increase, then drop back down as soon as your purchase has been filled.
When you buy a stock, you should have a good reason for doing so and an expectation of what the price will do if the reason is valid. At the same time, you should establish the point at which you will liquidate your holdings, especially if your reason is proven invalid or if the stock doesn’t react as expected when your expectation has been met. In other words, have an exit strategy before you buy the security and execute that strategy unemotionally.
If investing in single stocks may be too risky for you, consider investing in good growth stock mutual funds. Mutual funds are a simple, even boring, investment plan, yet they work well for most people. Of course, all investing requires a degree of risk; there really is no sure thing. But mutual funds are a great balance of reasonable risk and excellent returns. They have built-in diversification that will keep you from putting all your eggs in one basket.
Even when the stock price has performed as expected, there are questions: Should I take a profit now before the price falls? Should I keep my position since the price is likely to go higher? Thoughts like these will flood your mind, especially if you constantly watch the price of a security, eventually building to a point that you will take action. Since emotions are the primary driver of your action, it will probably be wrong.

In the professional world, one of the key concepts is diversification. Harry Markowitz is a Nobel prize winning economist and one of his major discoveries was that adding new asset classes can dramatically alter the overall risk profile of a portfolio. His finding was that a portfolio that contained very low risk assets would normally benefit from lower volatility and higher returns if a higher risk asset was added. This is due to the likely lack of correlation between high and low risk asset classes.

The solution to both is investing in stock index funds and ETFs. While mutual funds might require a $1,000 minimum or more, index fund minimums tend to be lower (and ETFs are purchased for a share price that could be lower still). Two brokers, Fidelity and Charles Schwab, offer index funds with no minimum at all. Index funds also cure the diversification issue because they hold many different stocks within a single fund.

Dollar-cost average: This sounds complicated, but it’s not. Dollar-cost averaging means investing a set amount of money at regular intervals, such as once per week or month. That set amount buys more shares when the stock price goes down and fewer shares when it rises, but overall, it evens out the average price you pay. Some online brokerage firms let investors set up an automated investing schedule.