Excuse me, do you speak English?
Many people in China presume that everybody from outside Asia speaks English. Although English is a widely spoken language, not every foreigner speaks it (or likes to speak it!). Granted, most Europeans who travel to China will have English (many of them will be fluent); it is still polite to ask first.
When travelling in non-English speaking countries it is even more important not to assume that everyone you meet can understand English. It's best to begin a conversation with, "excuse me, do you speak English?" In many cases the listener will be able to speak some English and will be happy you didn't just presume they could. If you can learn a few simple phrases in the local language it would be even more impressive.
Similarly, the word "foreigner" is commonly misused. A foreigner is someone that comes from a different country to your own. When you say "foreigner" you could be referring to a person from one of over 200 different countries. However, many students use this word to refer to Europeans and North Americans. A typical example would be, "foreigners don't use chopsticks". Japanese and Koreans use chopsticks and they are also foreigners.
If you want to speak generally about Americans, Europeans, Australians etc., you can use the term "westerners". But don't forget that this is a very wide group of people and it is often better to be more specific. If the person you are talking with is from Canada, use the word "Canadian", if they are from Greece, say "Greek" etc.
These mistakes are by no means serious. Nonetheless, there is no harm in trying to express your meaning more clearly.
The gloomy weather and exhausting work is killing me!
This miserable weather coupled with my heavy workload is killing me!
I am getting dark circles around my eyes, not to mention these disgusting zits!
The only cure is to get away to an island resort.
The only thing to do is escape to an island.
Sipping cocktails on a sun-drenched beach.
Sipping tropical cocktails in the sunshine by the sea.
Better yet, to have some romantic flings!