Big blind play at 3/6 6 max

[arizona]

After 70K hands, I am beginning to suspect that my blind play needs some work. Specifically, I believe I may be going too far in my big blind defense. How aggressive should I be post flop when defending my big blind? When do I give up and fold? In what situations should I just call? Here are my stats:

BB won per hand from big blind: -.15

Won $ WSF from big blind: 31.16%

When defending the big blind:

fold %: 40.7%
won w/o SD: 20.2%
WSD: 39%
Won $ at SD: 47.5%

Any advice is greatly appreciated.