1. Consult with the appropriate police station on your route and time of travel.
2. Stick to the main streets that always have some passerby's and traffic. Never go into any alleys or side-streets.
3. Get a sense of what other bikers are wearing and copy them. Do not stick out. Do not ride a $4000 shiny bike with a club jersey.
4. Consider NOT lighting yourself up so much. Tail lights and street lights are usually enough for cars behind to see you. A head light that announces your coming to every street thug should be avoided.
5. If legal (or even if not) clip a mace spray to the shoulder strap of your bag.
6. Carry a cell phone where you can reach it quickly as well.
7. Become a confident city rider. Take an entire lane. Stay away from the curb as much as possible.
8. Don't loiter at stop lights. Either bust through them (safely) or time the light so that you never stop.
Finally if you are a woman it is an unfortunate fact that you will get hassled more often. If you have long hair tuck it up underneath your hemet. Wear baggy clothing. No PINK!