Enter the castle, get kicked out, go through a dungeon, rescue Zandalor, let him teleport you to the council hall, clear that smallish area, get the council quests.
I would at least clear the Rivertown sewers before entering the castle. You may want to do some of the Verdistis quests first, as well, but you are at a high enough level you don't need to. At least visit the Ducal inn cellar, and get the quest to steal back Finnigan's lockpicks (if you have the
patch installed they are unbreakable, and give a nice stat bonus while in your inventory). If you started the game after installing the patch, you can complete the quest and buy them back, otherwise you can just never return them.
