Ethan
Selim is a tough guy, make sure you have a decent weapon and a ring and plug equipped, preferrably a set.
Food that both heal and give +attack/virility is also useful.
Selim is a Top, so start with Winking, and then Cupping his Balls.
If you haven't learned the "Wink"-technique yet, rescue the Librarian so you can repair the Library first.
Good luck!