Siri understands natural language, and can respond to a wide range of questions and commands. So there really shouldn't be a learning curve for Siri. But in fact you can learn ways to use Siri better, especially if you have a clear understanding of how it can help you. TiPb has posted a list of Top 10 Secret Siri Commands. There's nothing "secret" about them, but this is a great list for helping you get a better idea of some of the things that Siri can do.