I've been working on a project this week that has a bunch of layered objects. And it reminded me of today's tip, which I do instinctively, but that not everyone knows.
In InDesign and Illustrator, hold down the command key when you select objects that are stacked. Each time you click, it will cycle through the objects underneath that click point.
For example, you have a stack of three objects. You command-click on the stack. The first click selects the top object. The second click selects the middle object. The third click selects the bottom object. The fourth object selects the top object again and the cycle continues. (Bonus tip: If you command-option-click, it reverses the cycle order.)
It's really helpful when you have a complicated document.