Most of my stuff tends to be earth tones, simply cuz that seems to be the predominant colors in most gear. Green bag and tent (civilian colors, not OD), I prefer BDU pants, have a dark green jacket and black fleece (which were gifts). But, I'll usually pack regular T-shirts, usually royal blue or white. Sometimes I'll also pack a hideous orange-yellow fleece vest, or if it's a shorter trip, a red soft shell jacket.

The bandanas are a great idea I might steal. I've also found a few stores here that sell orange and bright pink duct tape. Maybe throw a few rolls around the Nalgene bottle?