"to someone" or "for someone"?

We usually use for when something/someone has an impact on someone:

• cause trouble/problem for sb

• convenient for sb

• good for sb

• healthy/unhealthy for sb

• It is important for you to …

But sometimes, both for and to can be used for some adjectives when something has an impact on someone:

• Breast-feeding is highly beneficial for/to newborn babies.

• dangerous for/to sb

• useful for/to sb

We basically use to when it is about opinions or attitudes towards something/someone:

• sounds good to sb

• unclear/ridiculous to sb

• cruel/rude to sb

• friendly to sb

• My family is important to me.