Beth Chase has some great suggestions for NPO board members: 10 Ways boards can reduce their personal liability risk.
All 10 are great ideas. Two that I think have particular value:
Insisting that board meeting minutes only record decisions made.
Avoiding completely any conflicts of interest, fully disclosing any potential conflicts and assuring any disclosures are included in the board minutes.
If you get into a serious conflict of interest mess in California, the Attorney General could sue the organization to have you removed from the board and then sue you to reimburse the organization for any losses incurred.
Full disclosure and board approval of possible conflicts can prevent a lot of problems.