The way I practice is once the mind is calm then I pick a theme to contemplate and use thought to reflect on the theme and then observe what's happening in the mind. For example, to contemplate impermanence you could start by looking at one of the five aggregates such as perception and saying, "ok, is perception impermanent or permanent?", then just drop the thinking and clear the mind and observe. You might see that perception changes from perceiving one object to another, or you may see the very object you perceive as changing. You can even use physical objects, like a knife and label it in different ways to observe the way perception changes. You could label it a tool, and observe the way the mind creates it as a tool, then you could label it a killing device and observe the way the mind perceives that. Then you could try not creating it as anything at all and just see it as it is, without adding any qualities to it. These are just examples, but if you ask the right question and then just observe with bare attention to find your answer you can gain some very deep insights. Anyway, this is just the method I use, but I thought it may be of some help.
"The heart of the path is quite easy. There’s no need to explain anything at length. Let go of love and hate and let things be. That’s all that I do in my own practice." - Ajahn Chah