This is the most straightforward approach. It involves avoiding banks or investments that you regard as unethical (or as especially unethical). Many people taking this approach will simply avoid all mainstream banks. Others might rule out any bank that invests in particular industries, such as arms or pornography, although this information can be hard to obtain.
This approach can also be taken by banks themselves. The Co-operative Bank is the most prominent example. There are a number of sectors in which it will not invest, and it will not offer accounts to organisations that it regards as particularly exploitative or immoral. The development of this screening policy has been undertaken in the light of regular consultation with customers.