When choosing an online broker, you have to think about your immediate needs as an investor or trader. If you are a beginner, you may need a broker who has great educational material about the stock market and other financial markets. This is one of the key reasons TD Ameritrade is our top pick for beginners. A number of brokers also allow for paper trading prior to funding an account, giving you an opportunity to learn the platform, sample the available assets, and test out the trading experience without risking real capital.