In one sentence, describe what the following article is about:

Once you have established some stock holdings, and you have a handle on how the buying and selling works, you should diversify your stock portfolio. This means that you should put your money in a variety of different stocks.  Start-up companies might be a good choice after you have a base of older-company stock established. If a startup is bought by a bigger company, you could potentially make a lot of money very quickly. However, be aware that 90% of startup companies last fewer than 5 years, which makes them risky investments.  Consider looking into different industries as well. If your original holdings are mostly in technology companies, try looking into manufacturing or retail. This will diversify your portfolio against negative industry trends. When you sell your stock (hopefully for a lot more than you bought it for), you should roll your money and profits into buying new stocks. If you can make a little money every day or every week, you’re on your way to stock market success. Consider putting a portion of your profits into a savings or retirement account. An IPO is the first time a company issues stock. This can be a great time to buy stock in a company you believe will be successful, as the IPO offering price often (but not always) turns out to be the lowest price ever for a company’s stock. The only way to make a lot of money in the stock market is to take risks and get a little bit lucky. This does not mean you should stake everything on risky investments and hope for the best, though. Investing should not be played the same way as gambling. You should research every investment thoroughly and be sure that you can recover financially if your trade goes poorly.  On one hand, playing it safe with only established stocks will not normally allow you to "beat the market" and gain very high returns. However, those stocks tend to be stable, which means you have a lower chance of losing money. And with steady dividend payments and accounting for risk, these companies can end up being a much better investment than riskier companies. You can also reduce your risk by hedging against losses on your investments. See how to hedge in investments for more information. Brokerage firms will usually charge fees for every transaction that can really add up. If you make more than a certain amount of trades per week, the Security Exchange Commission (SEC) forces you to set up at institutional account with a high minimum balance. Day trading is known for losing people lots of money as well as being stressful, so it is usually better to invest over a long period of time. Once you start making serious money in the stock market, you may want to talk to an accountant about how your profits will be taxed. That said, while it's always best to talk to a tax professional, in many cases you will be able to adequately research this information for yourself and avoid paying a professional. Trading in the stock market is like legal gambling and not an honest investment in the long term period. This is where it is different than investing, which is longer-term and safer. Some people can develop an unhealthy obsession with trading, which can lead you to lose a lot (even all) of your money. If you feel like you're losing control of your ability to make rational choices about investing your money, try to find help before you lose everything. If you know a professional who is smart, rational, objective, and unemotional, ask that person for help if you feel out of control.

Summary:
Diversify your holdings. Reinvest your money. Invest in an IPO (initial public offering). Take calculated risks when selecting stocks. Beware of the downside of day trading. Talk to a Certified Public Accountant (CPA). Know when to get out.