Strangely enough, non-native English speakers seldom have chronic problems with these. If it does come up, it comes up once or twice and never again. Native English speakers are the ones with habitual problems with these words – probably from learning them incorrectly or constantly seeing them being incorrectly used.
I need to try to remember the difference between ‘Affect’ and ‘Effect’ but I’m rubbish at the rules of English Language!