Thats a very deep subject. Much like trying to tell someone who to use color design effectively. Its something that will take time over the years to really learn.
But some very basic hints to get you started.
When you stumble across something where you do notice the light, say a building that has been lit up creatively, or light bouncing off a skyscraper and sprinkling the near buy building with interesting light, take a moment to stop and really look at whats happening with the light, and why you were drawn to it.
The same goes for late afternoon light in a landscape. Take the time to park yourself in front of the scene, and watch how that light changes as the sun starts to get closer to the horizon. It will create shadows and highlights on your landscape and there will probably be a point where you find the light is just perfect. Take a series of images during the whole process so you can examine them in more detail later.
Read about lighting design and look at the examples. Not just photography, but light design for home interiors, architecture, garden/patio lighting design, etc. Look at the various ways the light is used. It will help you see the variances in various lighting methods and techniques.
When you are standing there in awe in front of a gorgeous sunset, make sure you take the time to turn around. That same sunset will be throwing some gorgeous light everywhere, behind you, to the sides, etc. The best landscape shot could be the scene behind you, and not the sunset in front of you.
When you look at a really nice landscape image you admire, look at the lighting and image how it was lit. Where was the sun? What time of day was it? Is the sun high in the sky, or low along the horizon? Were there some clouds in the sky creating a nice pattern of shadows in the landscape? Trying to determine how something was lit is a great way to learn about lighting. It makes you think light.
Hopefully, it will help you start noticing how the light is playing across a landscape, and help you plan for it and capture it. You'll start to see clouds as diffusers in the sky, and shadow patterns on the ground. And you may find yourself thinking that the partially cloudy skies would cast some nice highlights and shadows across a valley floor you visited before. You would be thinking about the light ahead of time, and planning the time to arrive at the valley to capture the best light. You've previsualized your lighting, and are now working on how to capture that light. You've 'seen the light' so to speak.
Or you may find yourself thinking that you want to capture the sunlight just scraping along only the tops of tall grass in a field. You would know that you need to be there in the late afternoon to have the sun in the right postion to do that, and it would be that nice afternoon glow to boot. You would have 'seen' the light, and then planned your trip for the right time to capture it.