I just did a culture victory, did some things right and some things wrong, here are my thoughts on what I'd do:
Policies:
* Tradition (for the 33% bonus to Wonders early on b/c a lot of wonders help toward Culture victory)
* Piety (and by extension, NOT rationalism) for all of the massive bonuses, capstone being 2 free social policies
* Patronage (b/c city-state stuff goes a lot further, and getting free great people eventually from that bonus is huge)
* Freedom (for policy discount and culture boost; thanks Bhavv for the reminder of where this comes from)
The other one is flexible. Once you pick one path stick with it though since completing 5 entirely is a tall order, no detours.
Wonders:
Any wonder that either boosts your culture or reduces culture cost of social policies. Sistine Chapel and Cristo Redentor are two huge ones, but I know there are tons that I just can't think of off the top of my head. May also want Great Wall even though it is unrelated b/c it will help a lot if AI declares war on you, but that is a nicety not a necessity.
Try to spread at least one wonder per city. There is a policy that increases culture quite a bit in any city w/ a wonder.
Buildings:
Temple, Monument early -- this is a good use for gold to buy 'em up. Workshops and other production boosts as well.
Focus:
Production of course, but also gold to buy buildings and units you have no time to build. Build it up fast.
Diplomacy:
Stay non-provocative but strong. Befriend city-states when you get to that point by accomplishing as many quests as possible. (Don't pay gold until after you get a couple of Patronage promotions...at least the first one...but also start at 20 and gold goes further are great civics.) If possible, befriend a military city-state as well so you keep up your defenses.
That's not comprehensive but at least gives some thoughts. Good luck!