You can find a lot of information in guide: https://docs.google.com/spreadsheets/d/1kk1nVwdcqxsqkysRpLgMoRE0wKDOmMXYfxKpDsBlmas/edit?pli=1#gid=880947664
You can't gain much points with every character yet. For example you have to wait to have more stuff with Logan. To make Bernard naked - use love potion on him. He won't like it though and you will lose some liking points. The Northcrest story is not progressed yet, so nothing after showing the letter.