To @herbgee's post, you can see how I've summarized this in my "condensed" guide here and how I took it and adapted it for my own playstyle here. Again, my apologies to @Stephen Longshanks for pushing my Arc to 80.The guide was written long enough ago that the Oracle didn't exist and (maybe, I'm not sure) people weren't routinely leveling their Arcs to 80. Cosmic Raven is long gone and never finished it, so you might want to keep that in mind. Players are generally much more Arc focussed now, although @Stephen Longshanks does not approve!
But, you'll see in that post that the Oracle doesn't factor in. I built it and leveled it to 5 or so early on to help with happiness, but I ended up deleting it and building Hagia Sophia once my city was big enough to handle the space, but YMMV.