I wear a light greenish breathable shirt and dark trunks, but I just ordered a bright yellow cycling jersey. Coming from 20 years of motorcycling I have worn high vis for years and while I have read studies that say it really doesn't do a lot of good to get drivers to see you, I figure if it's that one diver that was going to hit me, it's done it's job. I also never assume that the car sees me, on a bike or motorcycle. Ride as if you're invisible because to most drivers you are.