Least Bosses DS1

Thief, Black Firebombs

Throw five bombs at asylum, darksign behind the little gate before asylum dies.
Talk to Oscar, leave Asylum (you can walk down and enter the fight through the door again), travel to Firelink

Get bones, lloyds from chests, bone back

New Londo Elevator
Pick 2k soul in valley(, RTSR, optional, makes it arguably more fun but loses a little bit of time)
Elevator upwarp, use 2k soul during (-> https://clips.twitch.tv/SparklingRoughOcelotThunBeast )
Get GCS, wrong warp to andre
Undead Parish bonfire, wrong warp to undead merchant, buy rapier + bow, rest arrows), bone back, SGS
Get Lightning Spear (keep https://puu.sh/zApgs/f4b8b6e4d0.webm in mind), kill Iron Golem (if no RTSR: 6 hits plus BF to stagger, 2 hits plus running attack to make him fall).

Dupe Iron Golem soul on elevator, make your way through Anor Londo (move lightning spear underneath the bow at some point, otherwise DT wont be in the right place after pickup), pray at archers
Take peach bonfire before OnS (that actually isnt peach in this route), lvl 27 STR, rest in END, pick up DT
Kill OnS, use IG soul on elevator, kill gwynevere, bone back

Warp to Undead Parish, equip Smough Soul
Kill Gargoyles, ring bell, bone back
Warp to Firelink, kick down Lautrec, get FAP ring
Dupe smough soul twice on elevator, go down to blighttown, use smough soul on waterwheel, take bonfire, level 28 END)
Trigger Quelaag, bone back, Quelaag skip, ring bell, bone back, warp to Firelink

Kiln Skip
Kill Gwyn (if no RTSR parry, you survive the fast attack)