(preview image - stupid thumbnail distortion)

I need some pointers here. I usually work with a lot of detail and very clean, in watercolour, with a rather precise pencil lineart. I've done that for so long that it's hard for me to do anything looser. Any pointers on how to get myself to loosen up and make this one really rough? Precise and clean won't work for this. I'm open to all suggestions including different media. (Apart from digital. I'm hopeless with that.)

Thanks in advance!