If you’re an active trader looking to try your hand at beating the market, you probably have a good idea of what you want in a brokerage: low costs, premium research, innovative strategy tools and a comprehensive trading platform. Below, we’ve selected the best online brokers in a variety of categories so you can choose one based on your personal priorities.

Let’s take a look at an example – if you want to sell 50 shares of Tesla, good market makers will buy your shares, regardless of whether they have a seller lined up yet. However, they may buy those Tesla shares for $300 each (the ask price), while offering to sell them to another trader for $300.05 (the bid price). That $0.05 is where your online broker is making their money.
While most online brokers do not offer international trading, some do. Nearly every broker supports trading American depositary receipts (ADRs), which offers US investors an easy, simple way to invest in foreign companies. However, if you want to buy physical shares of an international company, then you need to do your research. Interactive Brokers is the leader in this space but is built for professionals. For casual investing, both Fidelity and Charles Schwab offer international stock trading.
Access to current and historic market data – A day trader needs to be notified of market price changes as soon as possible to be able to act before an opportunity is gone or a loss is materialised. Historic data is necessary for technical analysis and backtesting of trading strategies. Not all platforms have a backtesting feature though, so check before you commit to a specific software.

The Intelligent Investor by Ben Graham ought to be required reading for every private investor. While the innovations he brought to stock analysis have long been outdated and the red flags he used to watch out for in a company's accounts are now regulated against by the SEC, many of his insights about thinking about investment still stand. For example, his description of Mr Market is still an excellent way of understanding how a crowd moves with the daily news.

Hiring human brokers to make phone calls and sell clients on investing is costly. Because discount brokers avoid this cost, they can pass on the advantage to customers in the form of lower commissions. A simple rule in the financial world is that clients pay the brokers' expenses, so the lower the brokers' expenses, the lower the fees and commissions.

The qualification for this award is simple: the lowest out-of-pocket costs. Tastyworks fits that bill well, as customers pay no commission to trade U.S. equities online, and there is no per-leg fee for options trades. Tastyworks has a unique fee structure for options trades, charging $1 per contract to open a position, while closing trades are free. In addition, there is a maximum of $10 per leg for options trades, so traders who place large spread orders are happy.
In the professional world, one of the key concepts is diversification. Harry Markowitz is a Nobel prize winning economist and one of his major discoveries was that adding new asset classes can dramatically alter the overall risk profile of a portfolio. His finding was that a portfolio that contained very low risk assets would normally benefit from lower volatility and higher returns if a higher risk asset was added. This is due to the likely lack of correlation between high and low risk asset classes.
The best way to practice: With a stock market simulator or paper-trading account. Many brokers offer these virtual trading platforms, and they essentially allow you to play the stock market with Monopoly money. Not only do you get to familiarize yourself with trading platforms and how they work, but you also get to test various trading strategies without losing real money. The link above has a list of brokers that offer these play platforms.