1. Don't say to someone riding right behind you "Ooh, look at the pretty sunset" then as they are looking make a sudden stop to take a picture.
I learned this gem of wisdom from my wife, as this is exactly what she did to me tonight.
Result: Scratched Brifter hood, torm bar tape and a twisted ankle (mine not hers).
I also learned (as if I didn't already know) that when crossing train tracks you should cross at 90 degrees and not veer in the same direction while looking for traffic etc.
I also learned this from my wife.
Result: A bent rear derauiller hanger and some minor scratches and bruises (hers not mine)
All in all, not the most fun bike ride of all time.