If you're just starting out as a new investor, you might not be rolling in dough. Fair enough. In that case, you'll want to focus on the account option that best serves your needs -- an account that has a minimum of $2,000 or less for initial deposits. Some discount brokers have no account minimums for getting started.
Don't have two grand in spare change hiding between the cushions of your couch? No problem. You can get started investing with as little as the price of one share of stock. One of the best ways to invest small amounts of money cheaply is through Dividend Reinvestment Plans, also known as Drips. They and their cousins, Direct Stock Purchase Plans (DSPs), allow you to bypass brokers (and their commissions) by buying stock directly from the companies or their agents.
We've got more details on Drip accounts in our "What if I can only invest small amounts of money every month?" Q&A.