Effective altruism is about the _effective_ part. Don't just donate to the charity or cause that _sounds_ good; look for where your money would provide the biggest impact.

If you want to save lives in general, look for the most _effective_ charity like that, which may be something like mosquito nets rather than a cancer research foundation. Don't just donate money to whatever is the most obvious charity advertised on television.

If you had a family member with cancer, look at which of N cancer foundations spend the money most effectively and donate there.

Often, altruism comes down to people giving money to the 'obvious' causes, which don't necessarily use the money effectively.