In this day of do-it-yourself investing, it's imperative that we are fully informed about the decisions we make. And with the Internet, there's no reason we can't make more informed decisions. Aside from helpful financial portals like (ahem!) The Motley Fool that provide news, commentary, and useful bits of how-to information, a number of other websites can also assist you in your quest to be a better investor.

You've already got your investment account set up with a discount broker like Ameritrade (NASDAQ:AMTD), E*Trade (NYSE:ET), or even Charles Schwab (NYSE:SCH) -- you do, don't you? -- and now you're ready to take the plunge into buying shares of stock. But before you do, you first need some critical information.

SEC reports and filings
Any investor who's going to take responsibility for his actions has to make the Securities and Exchange Commission's own website a must. Aside from the SEC's being the watchdog agency for the securities industries, and despite some deficiencies in its capabilities, the SEC site houses all of a company's reports and filings. If you want to find a copy of a company's quarterly reports, annual reports, proxies, or press releases, you'll find it here. And before you invest, you really need to read at least a company's last annual statement and even a few of the more recent quarterlies.

Yet as comprehensive as the SEC site is, it's not particularly useful except as a warehouse of data. It's taken other sites piggybacking on the SEC data to turn that information into something useable. Pay sites such as 10K Wizard have powerful tools to turn even the dullest financial report into something interesting. Its new "CompareWizard" allows you to compare two filings side by side, very useful when you're looking for changes from one reporting period to the next. Yet there are free sites that are nearly as good. SECInfo, for example, allows you to search for specific text within a filing (or in all filings) and highlights the sections that contain the words you're looking for. And one of the Big Four accounting firms, PriceWaterhouseCoopers, has made available its EdgarScan tool that neatly categorizes filings by type and date while also providing a "Benchmarking Assistant" that extracts financial data from the reports.

Watch the insiders
Who other than the senior executives at a company are more knowledgeable about its potential? When the insiders are buying company stock, that can be a very good signal it might be time to buy. Wading through the Form 4s that tell you which insiders are buying and selling can be time-consuming. Form4Oracle and NetSteering are two websites that make the task a lot easier, since they focus almost exclusively on insider buys and sales.

Read the fine print
Once you find the report you're looking for, you have to actually read through them. As Michelle Leder stresses in her superb blog, it's in the footnotes that you'll find the really juicy stuff that companies would rather you didn't read. Sure, the numbers are important, but it's the footnotes that put those numbers in context. Leder's blog goes through the filings and highlights examples of some egregious -- or, at the very least, noteworthy -- items that management tucks away in the fine print.

Others worth a visit
There are a few other sites dedicated to reading the filings posted at the SEC that are worth occasional visit, since the actions they keep an eye on might have an impact on your company.

There's 13D Voyeur, a blog dedicated to watching hedge fund managers and activist shareholders parry with management. Such communications are filed in a Form 13-D, and the Voyeur keeps tabs on 'em. The 10-b5 Daily is another esoteric blog that tracks class action lawsuits against companies, with an eye particularly fixed on suits that are dismissed or settled. What's a 10b-5? That's the section of SEC law that prohibits false or misleading statements from being made in connection with the purchase or sale of stock. It also happens to be the section of law most often cited in class action lawsuits in that aggrieved shareholders often claim that management misled them to invest and thereby artificially inflated the stock's price.

Last is The AAO Weblog, which tracks financial accounting issues such as restatements or pensions issues and their impact on companies. Jack Ciesielski, a member of the Financial Accounting Standards Board's Emerging Issues Task Force as well as a chartered financial analyst and CPA, also publishes the Analyst's Accounting Observer newsletter for institutional investors.

Foolish conclusion
There's no reason to let high-priced brokers and analysts make your financial decisions for you anymore. There is plenty of help for you on the Internet; it's just a matter of taking the time to find it.

Need to find some additional information? Check out these Foolish resources:

Charles Schwab is a Motley Fool Stock Advisor recommendation.

Fool contributor Rich Duprey does not own any of the stocks mentioned in this article. The Motley Fool has a disclosure policy.