As a programmer, I always find my inspiration from playing with new tools. We were already working on Apprentice for a bit when my artist introduced me to C2. I started playing with it, and pretty soon I was going "hey this is so much freer than RPGmaker, I bet I can make C2 do X". Then I would go and do X and thats how I got started. That wears off after a little while and I keep going out of professionalism, respect for my team, caffeine and raw desire.
If you are already familiar with the tools, get a design document going. Write up what your game needs to do, and try to pick the elements that will interact the most with the rest of the game and do those first.