Well, depends on your route, but usually will go;
(if you include some optional bosses, if you don't intend taking advanced routes as indicated)
Ornstein/Smough (LORD VESSEL!)
-a wild choice appears! (What will Player do?)
>Proceed through Dukes archive for Seathe?
> go to catacombs and defeat Pinwheel,then to Nito?
>Cease the Discharge and slay his mother (bed of Chaos) and/or his brethren (Fire Sage and Centipede Demon unless rank 2 in Chaos Servants)?
> Proceed through Darkroot Garden and take out sif (RIP gud boi) New Londo and take out the 4 kings?
>Then kill the Lord of Cinder himself
You could skip Taurus, Gaping and Capra by using the Master key starting gift, use the lift under firelink to new londo, go through another gate that leads to valley of drakes and blight town to navigate to Blighttown (duh), undead parish by going through valley of drakes, up to dark root basin, then to the garden and back to Andre and utilize the lift from Undead Parish to make a full circle on an interlocked and beautifully designed world. There's probably more that I'm currently forgetting (been years since I last actually explored the game)