The photography budget genie took a **** on my driveway so now I have some money to spend on gear. The only thing that is stopping me is that I am wondering whether it would be more worthwhile to shell out my bones on equipment or software.
My current kit works well but a flash or new lens could always be useful. On the other hand, I am constrained to editing tools like Gimp and Darktable. The tools I use now are OK but they're by no means industry standards like Photoshop or Bibble or Lightroom.
Which sort of investment will make the most difference in the quality of your work? Is it only a good idea to buy software if you know when and how you're going to use it?
Digging through my pictures, the majority of my usable shots are full-body and headshots of people outside a little before or after sunset. (the second golden hour and early nighttime) My biggest constraint is lack of natural light. More times than not, my subjects are moving so I can't raise the shutter speed. I've considered buying a flash but from what I gather they are hard to use appropriately outdoors.

