Yeah, I definitely noticed the "you pick two and deal with the third" thing.
I think the trick in most cases is to
Set the ISO as low as possible, depending on the lighting of the scene
Set the shutter speed, depending on if it's a moving target, such as animals
Set the aperture to even out the brightness
Play around with the ratios, as needed
That worked pretty well for my latest tries.
When I made the barn photo, I did have that composition in mind since I played around with compositions in the past, but literally had no idea what's important for the exposure triangle. I pretty much just pressed buttons until it was bright enough and was lucky it looked good, besides the grain