One of the things I've been trying to pay more attention to, is how colour sets the mood for things. I mean, reds and blues are obvious, but what about all the subtle colours and shades and pastels in between. The more you think about mood within the composition, the more it becomes a whole image and not just a series of things put together.

I've also been experimenting with how texture can contribute to the feel of a piece and add some interest to it. Especially with digital colour, having something other than flat shades can spice things up but texture can go even further. Misting, grit, pattern...anything can be useful in setting the atmosphere. My current favourite is controlled speckling!