Good is "Love thy neighbor as thyself."
Evil is failing to do onto others as they would do onto you.

This covers every moral issue except the Commandments about loving God. Make God your neighbor, make the world your neighbor for the purposes of these instructions and every sin or act or emotion possible is covered.

The beauty is not that you don't have to know what is ultimately good or bad for others, just that you filter their point of view through yours.

Would you want your neighbor to pollute the stream going through your property? No? Then don't do it to them. Would you want your son sent to an unjust war? Would you want your property stolen? Etc.. etc..