I have homegrown software. A lot of my best ideas have come from reading forums and either using posted ideas directly or with a few modifications. I've "stolen" a lot of ideas and I've been surprised by how many pan out to be reasonably good considering that so much chat is pretty mindless on some boards.
I'd have to say that the most elusive factor for the longest time for me was class and class/ability. It's amazing how many really good horses go off at 5/1 and better.
Maybe one of my best discoveries has been that you learn a lot more from a horse's good races than you do from the poor races. And competitive races are even better.