I know I can't attempt to paint anything unless I've already painted it in my head. I don't hope to figure it out along the way. To get inspired I look at art online and in books. I choose my subjects and imagine their layout, go shopping (for the lemons), set up the still life, do an actual sketch to get the dimensions right and then draw it onto my surface. The colors have already been picked and I know how I want to paint it and how it will look.
The interesting and fun challenge, is it same or different from what I imagined?