Took about 6k of gear to barcelona a couple years ago without issue.
- Always be attached to your bag, at restaurant between legs with strap wrapped round your leg, on your lap on public transport, in crowds placed on the front side of your body,
- Have a wrist strap attached to camera when using it (i use black rapids one)
- Use a discrete camera bag (I have a thinktank that looks like a book satchel)
- Have insurance, make sure its covered while abroad
- Be aware of your surroundings, I always make it apparent im watching my vicinity, they'll always pick on the weaker targets
- As above poster said, if someone approaches you just wave them away and shake your head as if you dont speak the language (even if its English)
- Don't over think things and enjoy your holiday, Barce is a beautiful city, all the gothic district (like old town) is awesome, and the hill with the museums and cable cars have great views of the city, theres tons of street art too for a street tog.
Edit: if you want to be really anal, put black electric tape over the camera brand/model, dont use a branded strap etc, these arent petty idiots, they can ID whats worth a few hundred euro and whats worth thousands, just another way of reducing the attraction.