Depends on the topic. As I'm not english-speaker, I often check out what wikipedia says about things I'm for example writing about to see how the things I already know are put across in English.
If the article lists it's sources and so on, and seems trustworthy, I tend to trust it, but for important stuff I check the scientific journals and so on.
I usually chack the sources if it seems odd or dubious, or if I'm interested, but for something like when some movie came out, I tend to trust it.