Many people regard chengyu as the golden key to the Chinese language and believe that learning chengyu will impress native speakers and take their Chinese to the next level. However, learning chengyu in the wrong way is likely to have the opposite effect ("oh, the foreigner is trying to use chengyu, how cute!"). Focus should be on chengyu that are truly useful and frequently used, the rest should be left for those who really like chengyu or for truly advanced students.