Hmm, we should turn this thread into a general advies one. There is so much to ask and learn about them, and the thread title is suited to it.
For starters: it is very irritating that relics often need a city item or oil. Was this done deliberately?
Seconds: do all (or even most) items that an advy picks up get used in one way or another, or are there some that can be sold outright?