There's a million models, but there isn't going to be one that's universally correct. The problem is that the inputs are generally too subjective and too noisy

There's a million models, but there isn't going to be one that's universally correct. The problem is that the inputs are generally too subjective and too noisy in any model that includes future earnings (there are some conservative ones that are based only only on past performance, but they will never match with an IPO valuation.) A great place to start is this book: Value Investing: From Graham to Buffett and Beyond ... by Bruce C. N. Greenwald ... most folks will say it's too conservative but it's a starting place.