While it won't make you a billionaire overnight, following these 5 principles can lead to better long-term investments.

Warren Buffett believes the stock market is hugely overvalued. We know that not because of his comments in the just-released Berkshire Hathaway annual report, which were ambiguous. We instead know it because of the status of the indicator that he has said is “probably the best single measure of where valuations stand at any given moment” — the ratio of the stock market’s total market capitalization to gross domestic product.