It took me over a year to get in the habit of using Siri, partly because she seemed so human-like. I was worried I'd say something dumb. One day I finally got it: there ain't no one listening. And ever since then I've used Siri with abandon. Lately I was surprised to discover that Siri offers a helpful guide to what you can say or ask.
To bring up Siri's guide to using Siri, simply say, "What can I ask?" Siri will then return an outline of things you can request or ask in 24 categories.
Each category, ranging from Apps, Messages, and Calendar to Restaurants, Movies, and Music, gives the category name and a sample request or question.
But each category also includes a submenu with a longer list of requests or questions, such as this list for the Apps category.
The Q&A category seems to be a miscellany of the sort of facts you can ask for. (Ironically, one of the items on the list, "Who's buried in Grant's tomb?" seems to stump Siri when I ask that, returning an empty result from Wofram Alpha.)
I also discovered that if I ask Siri several questions in a row, that Siri's previous answers are still available if I swipe down on the screen. They appear to stay there until you do something else on your device or it goes to sleep.
And I discovered that often when I ask a question, especially something that Siri doesn't understand, I can swipe up on the screen to see a list of sample requests.
