Sometimes you just have to 'GET IN THERE' and get your shot. While traveling, sometimes you can feel like you're imposing especially when you have your massive camera flashing in peoples faces. The best thing to do: Smile. I never like to make people feel uncomfortable or take their photo when they don't want it taken. (Though sometimes this does happen) So...sometimes I'll quickly grab a shot and hope the people don't mind. Otherwise I smile, and if they don't speak my language I hold up my camera and gesture. "eh?......big smile" 100% of 96% of the time people say yes.
When people do not speak your language it's very helpful to smile and SHOW them your photo! Let them SEE the AWESOME photo that you took of them. Most of the time they'll smile and laugh. Sometimes I take a photo with the person just to show them that it's ok. :) And then SCORE you've got a nice memory with an nice old lady or a group of good lookin' soldiers.
Sometimes you just need to get in there and TAKE your shot. You don't have time. Sometimes you have to look like a gomer to get that cool shot of a bird. ;)
Below are instances where I was so close to my subject I didn't want to make them feel weird or get yelled at by 'stealing' a photo of them so I simple asked. Seriously, it's worth the shot!
Get out there and work it. Don't be shy and remember...you're not a tourist..you're a PHOTOGRAPHER!
(okay, maybe a little tourist too ;)