I do this with moodboards. I scour the internet, magazines, books... for images, colours, details that in some way represent something about the atmosphere that I'd like to achieve as a whole... or that give an idea of the feel of the costumes... or the staging.
In the case of "The Ugly Bug Ball", I start by collecting all sorts of pictures of bugs in general as a starting point:
I choose the ones that 'talk' to me in some way - in this case, it soon becomes apparent that the vibrancy of the colours is going to be fundamental to my play - and I try to communicate this into a whole collage of other images that also show the same idea:
They're also a great way of expressing many concepts at once. My colour moodboard, for example, might represent the palate of colours I'd like to use across the production as a whole (in the set and costumes etc) but at the same time, it also manages to convey a sense of the 'explosion' of colour that I'd like to create and, in turn, communicates a sense of energy, vibrancy and dynamism that I'd like the play as a whole to present. It is starting to become clear that I'd like this play to be a 'carnival' of colours.
To help define the look of the costumes, again I turn first to nature:
And then try to represent the elements that have inspired me in a moodboard. In this case, I'm focusing on textures (silky sheens, fur, velvet) as well as the swirling, almost metallic patterns of petrol or tie dye:
Sites like www.shutterfly.com are a great way to develop mood boards - collect all your inspiring images together and share the link with anyone else you are working with. They can also add their own images, comment on photos, and it gives everyone a common focus.