These are some of my chosen writing tools. We've got three different notebooks, a sketchbook, several different colours of pens, and a pencil. Though you can see that, actually. I write on a computer, but I like to compile my thoughts and inspirations in notebooks.
I mostly use the black notebook, and it's slowly starting to fill with absurd notes like, reminders to pay my application fee for CSUCI, bits of dialogue ("I rather think I have a better grasp on English than you do."), and chunks of snark like "He is a middle-school girl, okay?"
The big one is strictly for my current project. So far, I have notes on the species I've created (also a drawing), decisions on how to feel about certain characters, and quotes that act as inspiration. This is where the different colours come in handy. Each has a different purpose, though, truth be told, I haven't totally figured out what yet. Still useful.
Seriously, though, I am literally never without something to write with and on. When I went to the Renaissance Faire and couldn't find the little circle notebook, I made one out of sketchbook paper. I'm clever like that. My iPad works in a pinch as well. At the end of the day, I just collect relevant things into the black notebook, and one of these days, I'll do the same with my big notebook.
Finally: a sketch of a character and some really messy writing. It's all good, yo.