Overall commission costs can also be affected by new customer promotions. Brokers may give you a chunk of free trades based on your deposit amount. If your deposit gets you a substantial number of free trades, that can write off otherwise higher per-commission costs. Ally Invest offers small incentives for deposits as low as $500. Fidelity Investments, meanwhile, has a higher barrier for entry — it takes a $50,000 deposit, but then you'll get 300 free trades.
Choose your trading partner wisely. To trade stocks you need a broker, but don’t just fall for any broker. Pick one with the terms and tools that best align with your investing style and experience. A higher priority for active traders will be low commissions and fast order execution for time-sensitive trades (like our picks for best online platforms for active traders/day traders). Investors who are new to trading should look for a broker that can teach them the tools of the trade via educational articles, online tutorials and in-person seminars (see NerdWallet’s round-ups for the best brokers for beginners). Other features to consider are the quality and availability of screening and stock analysis tools, on-the-go alerts, easy order entry and customer service.
Thinkorswim is a particular standout in options trading, with options-trading tabs (just click “spread” if you want a spread and “single order” if you want one leg), plus links that explain the strategies on the order page. Its Strategy Roller feature lets investors create custom covered calls and then roll those positions from expiration to expiration.
E*TRADE does require an investment minimum for new brokerage accounts ($500), which may seem like more than a novice would like to throw in. But you’ll need at least that much to see real growth, and compared to the minimums of traditional brokerages, $500 is an incredibly welcoming threshold. Additionally, if you can commit to a $10,000 deposit, you can get 60 days of commission-free trades.
Devote no more than 10% of your portfolio to trading. Even if you find a talent for investing in stocks, allocating more than 10% of your portfolio to individual stocks can expose your savings to too much volatility. Other ground rules to manage risk: Invest only the amount of money you can afford to lose, don’t use money that’s earmarked for near-term, must-pay expenses (like a down payment on a house or car, or tuition money) and ratchet down that 10% if you don’t yet have a healthy emergency fund and at least 10% of your income funneled into a retirement savings account.
If you want to learn more about how to invest in a stock, check out the directory of Investing for Beginners articles I've written, sorted by topic or head over to my blog for more esoteric and advanced topics that aren't particularly appropriate for beginners. Whatever happens, remember that stocks are just one of many types of assets that you can use to build wealth and become financially independent. 
Not everyone who buys and sells stocks is a stock trader, at least in the nuanced language of investing terms. Most investors fall into one of two camps. Depending on the frequency in which they transact and the strategy driving their actions, they’re either “traders” (think Gordon Gekko in the movie “Wall Street”) or “investors” (as in Warren Buffett).
Worth noting: A 401(k) is a type of investment account, and if you’re participating in one, you may already be investing in stocks, likely through mutual funds. However, a 401(k) won’t offer you access to individual stocks, and your choice in mutual funds will likely be quite limited. Employer matching dollars make it worth contributing despite a limited investment selection, but once you’re contributing enough to earn that match, you can consider investing through other accounts.