The greatest compliment my wife ever received was to have a Brit stop her and ask for directions!
Of course, she swears it was actually George C. Scott (in the country making a film).
We always try to dress like the 'natives' whenever in Europe. And we seldom speak above a whisper in public! Loud talk's a sure tip off that we are 'Americans', we just hope that by the time we're recognized, we'll have made a better than 'the ugly American' impression on the locals.
And I highly encourage any type of traveler to study a bit about whatever area you might be visiting (even if it's just to the nearest state!). It's even easier with the Internet but there are great books (Steve Ricks, anyone?), also (available free in most libraries!). So there's no excuse for not knowing a little about the location you visit and it usually makes a good impression on the locals, showing that you care enough to want to know something other than where to buy souvenirs!
If you're willing to try some of the native language, so much the better! At least "Hello!", "Thank you." and "Which way to the US Consulate?"
BTW, the hardest language we've ever come across is in Wales!