The above image has circulated the internet for some time I think. Most of it is true for me. When I learned about light, my photography dramatically improved. Light probably falls under technique and coincidentally also around the time I started uploading one photo per motivation/set.
I got motivated to learn about light after seeing gorgeous images being produced by Adam Patrick Murray. I loved how clean and sharp the image looked. The key light is soft, the rim light makes the model "pop" from the background. Seeing this kind of work encouraged me to learn.
Photographer: Adam Patrick Murray
Model: Amie Lynn
A few friends in my photography network introduced me to off-camera remote triggering systems, manually controlling flashes, basic light modifiers (like a brolly and reflector), and how to measure light using a metre.
I recall spending a lot of time reading portrait photography magazines and watching tutorials on Youtube. A lot of resources are free. You just have to know where to look.
I initially tried using 500W hot lamps, but they were very uncomfortable to work with. I switched to the portable flashes, 3x YongNuo YN560II's in addition to my existing Canon 430EXII flash. The advantage of the Chinese brand of flashes was that they were far cheaper than the Canon one, and they are easier to control on-the-fly. The Canon flash buries power adjustment under multiple menus. It also has a power saving feature which puts the flash in sleep mode which is quite annoying.
For remote triggering systems i started with YongNuo branded kits recommended by the local store, but they broke twice under warranty for no reason at all. I then bought Aputure Trigmaster II and have had much better results with those. I now use Pocketwizards because of their reliability despite the higher costs.
Always buy remote triggers from a local store even if it costs more than ebay. They break so easily it's just not worth saving a few dollars. Have them replaced under warranty if you value your time.
One of the other aspects of flash photography I learnt was to recognise the characteristics of light on any subject or surface. Basically I learned to reverse engineer the lighting in an image so that I didn't have to ask the photographer how they did it. We are bombarded with thousands of advertisements each week. It would be very hard not to start seeing patterns or characteristics of light, and how it is projected on to a subject. Are the shadows hard or soft? Where is the light coming from? How many lights can you see? Etc.
If a photographer leaves a lighting diagram explaining their scene. Learn to read it!
I studied numerous pop-culture magazines, gaming and movie posters, advertisements and commercials, fashion and product catalogues, wedding albums, and high end photography productions to learn about light. I learned to recognise the type of light and common modifiers used. I paid particular attention to the colour temperature, direction, distance, intensity and shape of the light source in relation to the subject. This knowledge is then applied to my own creations. Doing this over and over, tweaking my processes and workflow as I went, was how I learned to take better photographs.