The InDesign tutorial that I received when starting on my Head First book was helpful, but there were some super-useful InDesign features it didn’t include. I shared this list of my favorites with my fellow authors, and figured I would copy it here…

• Libraries: I set up an .indl file with about 6 objects, each with many embedded and anchored components. Whenever I needed a page element, I dragged and dropped it into place, and deleted the subcomponents I didn’t need. Libraries were probably the single biggest time-saver I discovered. Adobe help: Use Object Libraries
• Anchors: Great for any object that you need to keep its position relative to another object, such as an annotation arrow that you need to point to a particular line of code, or a text box showing output that you need to stay next to a code sample. Adobe help: Anchored Objects I usually use “Custom” positioning, with X relative to the anchor marker, and Y relative to the line the marker’s on.
• Auto-sizing: Almost all your text frames should have auto-sizing turned on, either horizontally, vertically, or both. I set up a library with appropriate text frames I could drag-and-drop, but I believe you can also set up properties for the default text frame. Adobe help: Frame Auto-sizing
• Quick Apply: Select an object, press Ctrl-Enter, and begin typing the name of any menu item, text style name, or whatever else you can think of. It’s like Alfred for InDesign! Better than trying to remember all those complex keyboard shorcuts, and it even lets you use stuff for which no shortcut has been assigned. Adobe help: Quick Apply
• Group objects: Another, simpler way to ensure objects keep their positions relative to each other. Adobe help: Grouping Objects

And remember, search engines are your friend! If there’s something you want to do but you don’t know the name of the feature, just type “indesign” into a search engine, followed by a brief description of what you’re looking for. You’re almost certain to stumble upon a forum post with the answer.