From my 4 months of commuting, here are the basics...

- Take the lane. The whole lane. All the time. If you're on the stripes, you'll get no room by cars whizzing by.
- When possible, use side roads instead of main highways or busy streets.
- Helmet. I've already crashed once (my fault), and the $40 I spent on it no doubt saved a $4000 hospital bill.
- Seat bag full of tools, tube, tire gauge, batteries, etc.
- Headlight. My $30 light needs upgrading, but it's good enough to see & be seen.

- And without a doubt, the most important safety tip/tool you can use is a PLANET BIKE SUPERFLASH. I got buzzed 2-3 times a day before I got my SuperFlash. In the 3 months since I got it I've been buzzed twice.