Once you beat O&S you get something that makes getting around a lot quicker, and the game in general gets easier (though there are still some major challenges for sure).I had no clue in what order I should be going to the different places, but I was really lucky to get the sword from the first black knight you encounter and so I've had a big advantage so far and I didn't end up having that much trouble down in Blighttown, I have the master key too so I could get in through the back and go straight to Quelaag, she was a b**** to beat, but that massive chest was worth it.
Made it to Anor Londo and I'm just trying to get to a point where I can beat Ornstein and Smough, been going with a INT build with Moonlight Butterfly Horn as my weapon of choice now and I think the catacombs are where should go next, but it has given me a newfound fear of skeletons.
No idea how long it'll take to beat, but I'm already planning ahead for the sequel, I needs it.
If you kill the necromancers in the catacombs then the skellies don't come back to life. Or alternatively get a divine weapon, that will keep them down as well. If I recall, the spears that drop from the silver knights in Anor Londo do divine damage so you dont' even need to make one if you have to the stats to use one of those.