Something this simple, with crochet - maybe collect a ball of wool (bought, commercially dyed, hand-dyed, homespun, etc.) until I have enough of a bunch of colors that work well together, and start working.
Mizzie. Consider embellishing grey sweater. Look at the various open knit sweaters for some subtle embellishment around cuffs or collars. Black and silver on grey perhaps. Clashing colours on others. Interview some of the interesting yarns you have acquired with no idea how to use them. This could turn a sweater into a real part of a particular outfit. Good inspiration here!