These feel like stating the obvious, but maybe outside LW they wouldn't:

• Expect the judgement of evidently rational players (such as Peter Thiel, Elon Musk, and probably many others I'm unaware of) to be extra trustworthy. Do what they're suggesting, or what becomes profitable once their suggestions have been implemented by others. (For example, Elon Musk said fully electric hypersonic VTOL jets are possible. He's rational and knows a lot about electric propulsion and aerospace, so this heuristic means believe him even though he hasn't demonstrated it. So when looking at aircraft propulsion business, favor companies at least looking at electric propulsion.)
• Expect economic upheaval created by self-driving cars and other autonomous drones in the next ten years. Avoid investing in any business insufficiently aware of, or insufficiently preparing for, that. Specifically, avoid brick-and-mortar retail with (narrow ranges of) products that could be shipped via drones.
• Expect the education bubble to burst at some point. Avoid investing in business that would suffer in that case (e.g. real estate near universities), and invest in companies that benefit from it (e.g. online education providers).

Maybe if you make a detailed scenario study of a world where all of these are true, you can find more indirect opportunities. All those drones should create a booming market for ultra-low power radar devices, for example. But that's hardly an LW specific idea. I think rationality mostly helps you reduce uncertainty about probabilities, but not necessarily into any particular direction. I suspect its main value might be that with greater certainty about how things that haven't happened yet will eventually turn out, you can more confidently think another step ahead and take opportunities that other people aren't sure will even arise.