One way to start investing in stocks as an 18-year-old is to open a brokerage account with a reputable online broker. After funding the account with your initial $100 investment, you can start researching and selecting individual stocks or exchange-traded funds (ETFs) to buy. To make money with stocks, you'll want to focus on buying shares of companies that you believe are undervalued and have the potential for strong growth in the future.
To turn your $100 into $1,000 or more, you'll need to be patient and disciplined, and aim to consistently earn returns that are higher than the average market return. One strategy for doing this is to invest in a diversified portfolio of stocks and ETFs, and then regularly rebalance your portfolio to maintain your desired asset allocation. This will help you take advantage of market fluctuations and maximize your long-term returns. Additionally, you can continue to add to your investments over time, using the power of compounding to help your portfolio grow even faster. Finally, it's important to stay informed about the market and the companies you've invested in, and to remain patient and disciplined, even when the market is volatile.