European Travel + Safety
Knock on wood, I've never had a single problem during more than 40+ trips to Europe over the past ten years. However, a friend of mine did. We were having a coffee in London at a cafe just north of Oxford Circus when someone apparently managed to take a single credit card from his wallet. A couple of hours later, noticing the card was missing, he called Citibank and was informed it had been charged upwards of $500 [this was before chip+pin]. Lesson learned.
Keep your wits about you, maintain pace in your face, don't flash jewelry/money, and move quickly through areas where tourists congregate.
Riding the Tube and public transport, I am especially aware of my surroundings. Riding the Tube, I make sure my back is against the end of the carriage if I can't find a seat and when I get off the trains - especially at rush hour - I wait until the crowd exits the station so I'm not jostled heading out. On escalators, I'm always moving up/down - to prevent someone from standing right behind me and at the ticket gates I have my Oyster Card or day ticket separate from my wallet; so I don't have to be handling it in public.
Good advice about making a copy of your passport; make sure the photocopy is separate from your passport.
I generally avoid areas that I know are going to be crowded with tourists: Oxford Circus, Leicester Square, Oxford Street, etc.
One other consideration is atm's or 'cash points' as they're referred to in Europe: A friend's mother was robbed while getting cash during the day on the busy high street in upscale Hampstead Heath. The thief didn't know she was a tourist; but it just goes to show that it can happen to anyone; anywhere.
A new study out recently said you're more likely to be a victim of a crime in Oslo than Manhattan. For anyone who has been to Oslo, that's saying something. A couple of year's ago, confident of my mastery of Norwegian, I purchased the wrong ticket for the Oslo metro system at a vending machine and had to get it exchanged. The attendant - after realizing I was a tourist - went out of his way to caution me about the rampant pick-pocketing problem on the city's metro and trams. I was quite surprised to hear him be so blunt about it; but he was adamant. I didn't have any problems - riding day or night but even in pretty Oslo there are problems and we, as tourists, have to keep our guard up and not assume everything will be ok.
My final advice: don't use an iPod in public. Those white ear buds are an invitation to get robbed. iPods are a hot commodity in Europe [more expensive than the U.S.] and there have been reported muggings for them [along with cell phones]. If you want to bring your iPod, I'd only use it privately - especially in London.
Lecture over. Have fun.