Choose Mercenary and Fire Gem at start.
Kill Sword Master Saber and get your Uchigatana. Infuse it with Fire Gem. Level up ur STR stat by 1.
While obtaining Red Eyed Orb you can freely level up to 20 (into END/VIG) and upgrade Uchigatana to +2.
For that u need Pale Tongue. You can get it after fight with Fire Demon (with Siegward).
Then lighting the Cliff Underside bonfire or defeat the Curse-Rotted Greatwood in the Undead Settlement.
Now talk with Leonhard at Firelink Shrine and he will give you the Lift Chamber Key to the locked door below the Tower on the Wall bonfire. Head there, unlock the door, take the lift down and defeat the Darkwraith there to obtain the Red Eye Orb.
Enjoy your low level invasions, skeleton!
P.S.Also i picked up those rings,because u can get it in early game:
Fire Clutch Ring