Just for those trying to get this skill to increase faster... I never saw this explained clearly anywhere, but I found that it is only possible to effectively increase Etiquette by talking politely in Castles. One might think that talking politely to other "factions" with similar standards (i.e., Knightly Orders, Temples and Mages Guild) might help you pump that up, but as far as experience has showed me, it doesn't.

I don't know if Streetwise follows a similar behaviour, but it should, which should mean that it is a lot easier to increase this than the other.

pd