Use it all!
I often find that some of the most simple or fundamental techniques in photography are also the ones with the biggest impact. So when it comes to filling the frame, there really is not that much more to tell than: fill the frame with your subject.
Filling the frame does not necessarily entail a macro shot, although you often will go very close to the subject to fill the frame. But the point with filling the frame is that the “stage” for the subject is lost and only the subject is left. So a lot of storytelling and the relationship between subject and surroundings is gone when you fill the frame.
You can fill the frame when shooting, but if your camera has sufficient resolution, it is certainly also an option to crop the image in post processing and get the same effect.
In the example above, I chose to frame the image with a lot of context information. I could have gone much closer to the withered leave in the center and gotten a very different expression, focusing more on the withered vs living leaf relative to the rainy day scene surrounding them.
There is no right or wrong here – just different expressions. So it comes down to what story it is you want to tell and the expression you want to come across. Filling the frame is just one of many options for you to compose your image.
Related reading
What are leading lines in photography?
Mind the background in your pictures
