JPMorgan Chase CEO Jamie Dimon's letters are worth a read, too. And anyone who hasn't been reading Warren Buffett's letters can find all of them at BerkshireHathaway.com. Various studies, such as those by Rittenhouse Rankings, have linked candid CEO letters with companies that outperform. You may not understand some jargon or industry metrics in some good CEO letters, but you'll likely walk away at least a little smarter. Fool's school Resources for research: For best results when investing in stocks, do some deep digging into the companies you're considering first. You'll want to ensure that each is healthy and growing, with competitive advantages, a rosy future and an appealing price.