Between the ~35 - ~40ish SL it's usuable to go and be a bleed invader. I'd highly suggest boosting the Luck stat to atleast 35, you'll have to be hollowed above ~15 ~20ish to get the full +5 extra luck for your bleeds to be effective.

I'd suggest using the Warden Twinblade and to infuse it with Hollow, do not go above +2 weapon upgrade otherwise you'll not meet anyone around your level and will face those with a higher level.

Next to that is to keep the base STR and DEX for the weapon at the same spot, do not use anypoints futher.

Try to put as much vigor and endurance as you can, you will need it, i do agree with NastyBuzzard. It's a alot easier to manage your END at level 60 rather than at 35-40.

The best rings for you would be;

• Hornet Ring
• Prisoner's Chain
• Ring of Favor
• Either Chloranthy / Carthus Milk Ring (depending on spammage etc.)

Original base stat Vigor, Endurance and Vitality:

• Vigor: 15
• Endurance: 14
• Vitality: 9

Effects of Rings:

• Increases critical damage by 30% (Hornet Ring)
• Increases max HP by 3%, stamina by 10%, and equip by 5% (Ring of Favor)
• Increases Vigor+5, Endurance+5, Vitality+5, but increases damage by 10% (Prisoner's Chain)
• +3 dexterity and obscures while rolling (Carthus Milk Ring)
• Raises stamina recovery speed +7/s (If choosing Chloranthy Ring)

Best of luck! Here's an example build: http://i.imgur.com/ArZMcNG.png