Photo Organization

I like taking pictures. Specifically, I *heart* taking pictures of flowers, bugs and nature in general. 

I also, however, have gigabytes and gigabytes of pictures and they're so disorganized. I have five folders named New Folder(x). I have From Camera, From Phone, From iPhone, From Nikon, etc., which are basically huge photo drops that could be duplicates but my phone or SD card was full and I needed it so I'd just dump them all. 

They need sorted in a major way. Really, 95% of them need deleted. I'm frozen with not knowing where to start. Do I organize them by subject? By date taken? By....? 

Red Sky at Night...

Straight from the sky to the camera, no post processing whatsoever. The sky was beautiful last night.