You should be concentrating on Endurance and strength with each level up. It's also advisable to put a few points in Vitality and resistance before heading to blightown.
Head to dark root garden and get the elite knight armour and long bow. Whilst you're here, kill the moonlight butterfly- just summon the witch and stand back as she kills it in like 2 minutes. Easy! Get the divine ember and head back to the blacksmith. Upgrade claymore and halberd to +5.You won't have the endurance to wear all the armour so just wear the elite armour torso and leggings. Kill the capra demon (on your second attempt because you forgot about the dam dogs and got owned) .
Head to Depths and rescue Pyro man and get large ember. Complete the depths in human form to get more item drops from enemies and to kill Kirk the annoying phantom for loads of souls. The bonfire is a great place to farm souls and large titanite from the slimes and Eyes of Death from the smoking frogs. Kill the gapingly easy dragon (with Solare summoned) then head back to firelink shrine. Get the pyro glove, fireball, combustion and iron flesh from the dude you rescued. Upgrade flame to at least 5.
Return to the undead Asylum and get the rusted ring and painted doll. If you feel up to it take on the stray demon to get the titanite slab but I'm too scared too so will return later...
Head to blight town and get the shadow armour- wear the hood and gloves now. You should definitely get the Eagle Shield and use it from this point onwards. Make sure to pick up poison mist and power within pyromancies. In human form, make sure you kill Mildred so you can summon her in the Queelag Boss fight. Kill Queelag. Join the chaos covenant behind the fake wall and then head to demon ruins. Stand next to one of the moving egg carriers and let him rape your face. Head back to spider witch and wait until your face turns into an egg (I am not making this up!). Talk to Eingyi and buy his pyromancies and upgrade flame. If you have any souls make sure you spend them..even if it means going back to another merchant and spend any humanity by kindling bonfires! Suicide run into the demon ruins to get the Gold-hemmed Black outfit and then let flame tentacle demon kill you (it wont take much..). Wear the hood. Half of our outfit is done!
Now we need some more souls to buy the crest of Astora. Either farm them or better, do some co-op with people to defeat Queelag. Leave your summon sign outside where the fog gate was before the boss battle. You'll get 10,000 souls and 1 humanity a go. Head back to blacksmith and assend halberd to Divine +5 and claymore to normal + 10. You'll probably find your claymore is now more powerful than your drake sword so use that from now on. It would also be a good idea to upgrade a Falchion (found in blightown) +6 so you can make Queelags Fury sword when you get to Anor Londo. Buy the crest/key and then head back to dark root garden.
Your aim here is to join the forest hunters and collect some items. Get the stone and eastern armours. Go down and kill the hydra. With the eagle shield you can block all the head attacks and just swipe away at them- I didn't lose a single bit of health. Now for havel's ring. Go to watchtower and cast poison mist then open the door.Havel will be poisoned and die (might need to cast it twice). Get the grass crest shield too whilst you are in the area. Return to undead merchant and buy 100 poison arrows- this is very important for later! Head to blighttown via the shortcut through valley of the drakes and kill Shiva of the east and more importantly, his body guard. This is to get the darkwood grain ring and iron shield. Wohoo!
Sen's Fortress- just get through this bloody place and remember to activate the cage shortcut. Im human form, summon Knight Tarkus and defeat the iron golem. Finally made it to Anor Londo!
In Anor Londo you should be able to get strength to 24 and endurance to 35. Once at the Giant blacksmith make Queelags fury sword from the falchion +6 upgraded to +10 with the large titanite shards he sells. Also, get the claymore +10 to a Lightning claymore +4- if you did kill the stray demon you can make this a +5. The drake sword should be well and truly forgoten now! Make sure you pick up the Black iron set and upgrade the torso and legs as much as you can. You should now have the complete outfit. Now to prepare for THAT boss fight.