How much money should I invest in stocks? If you’re investing through funds — have we mentioned this is our preference? — you can allocate a fairly large portion of your portfolio toward stock funds, especially if you have a long time horizon. A 30-year-old investing for retirement might have 80% of his or her portfolio in stock funds; the rest would be in bond funds. Individual stocks are another story. We’d recommend keeping these to 10% or less of your investment portfolio.
When thinking about the mindset of investors, The Great Crash 1929 by J.K.Galbraith (reviewed here) should also be required reading. Typically, any sustained fall in prices - known as a bear market - is very destructive to wealth. However, as Galbraith explains wonderfully, each bear market is unique and is a reflection of the bull market that came before it. The book explains a great deal about the feedback loops that can exist when prices rise and fall as more people are either sucked into or forced out of holdings. It is the reference work about a very important slice of Wall Street history.
It’s best if you can automate your actual stock investments. Robo-advisors can do this for you, or if you must, you can manually buy stocks every time you receive a paycheck and have money in your savings or brokerage account. The important point is that you make regular investments so that you aren’t tempted to time the market. Regularly investing the same amount is a form of dollar cost averaging, and it helps reduce risk in your stock investments.
In that case, it is possible to invest passively in capital markets. This means that a private investor puts aside either a lump sum or an amount each month and the money is invested into a fund. That fund contains the savings of lots of other private investors and is managed by a professional equities investor. The fund will then be invested in an equity market (such as the NYSE) or a sector (such as energy).
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.

What would make me sell: Sometimes there are good reasons to split up. For this part of your journal, compose an investing prenup that spells out what would drive you to sell the stock. We’re not talking about stock price movement, especially not short term, but fundamental changes to the business that affect its ability to grow over the long term. Some examples: The company loses a major customer, the CEO’s successor starts taking the business in a different direction, a major viable competitor emerges, or your investing thesis doesn’t pan out after a reasonable period of time.