I must admit that I have never had any problems practising a language in the country where it is spoken. Yes, I did meet people who responded to me in English or German, but those were mostly people in the service industry and it was basically just a few set phrases that we exchanged in these situations.
Whenever I felt like striking up a conversation with somebody, I managed to do so. I simply tell people the truth, namely that I love their language and have a lot of respect for their country and culture and that I am eager to learn more about it. If someone still continued in English, I’d simply ask them to help me get a better grasp of their language by speaking to me in Italian, French, Mandarin, etc.
This ALWAYS worked. And if one day it should not work, I’d simply go on and try and find somebody else to talk to.
I should add that I don’t mind people trying to speak to me in German and/or English to get some practice but there is a limit to it. If I go to Japan, China etc. to practise my language skills I won’t talk to the locals for hours in English. I have noticed, however, that they do appreciate being given the opportunity to show their own skills and in most cases were more than happy to switch back to their native tongues after 15 minutes or so.
Unless you try to turn every passer-by into your private language tutor, I think you should be able to find at least some people you can have an interesting conversation with, provided of course your speaking skills allow for such conversation.
If I met a foreigner here in Austria who obviously wants to practise his German with me, I would never even think of switching to English (unless he isn’t able to make himself understood to me in German). But, of course, I would also have to be interested in talking to him in the first place. I would not have a conversation with anybody - irrespective of their linguistic skills - I don’t feel like talking to. If anybody wants me to go beyond the exchange of some polite phrases, chemistry does play an important role as well.
So, don’t be disappointed if some people keep switching back to English. You will definitely meet people who very much appreciate your obvious effort to learn their language and the better you get at the language you study, the easier it will be for you to find people to talk to.
As for the French, I can only attest to their readiness to help you with the language. I have always had a wonderful time in France. Just forget about all the stereotypes you hear. Like anywhere else, you may meet some narrow-minded people but I have found the French to be some of the nicest, most polite and helpful people I have ever met. Besides, I love their language