I've been riding seriously for 18+ months, in rural and urban environments in the South of England. I get nervous when I think about the accidents I read or hear about in the news, but I have never had any problems with deliberate harassment, and only a couple of times when people have been careless and I had to bellow at them (works incredibly well, bellowing).

Training and hi-viz are everything: I have lights for daylight running and a fluorescent jacket.

Jacket: http://www.amazon.co.uk/Blackrock-Workwear-Highland-Visibili... Headlamp: http://www.amazon.co.uk/Lumen-Cycling-Bicycle-Light-HeadLigh... Blinkies: http://www.amazon.co.uk/Cateye-HL-LD130-TL-LD130-Light-Set/d...

Also, learning how to ride correctly has made a huge difference, try this book:

http://www.amazon.co.uk/Cyclecraft-complete-enjoyable-cyclin...

If you want the reassurance of a helmet (I have mixed opinions) get a Specialized since they're made to a higher standard than most other brands.

Try to find quieter routes if you want to try riding. This app can help:

http://www.transportdirect.info/web2/journeyplanning/findcyc...

As can scouting your route using street-view, etc.

Try it, you should live :) And as OA says, you'll live well too.