Nail him on PRA loopholes and conflict law violations. Not exactly a groundbreaking strategy, but as a quick scan of this morning's top Rough & Tumble headlines shows, the "gotcha" route seems the way to go.
Supplement ban vetoes, PAC rent money, whatever, it's sure easier to get Schwarzenegger - or try to - on technicalities than to nab him on substance. Wonks, of course, would much rather trumpet his budget-plan cop-outs, his failures to accomplish much touted reforms, and his inability (unwillingness) to really deal with the legislature.
Schwarzenegger does owe some explanations on these conflict violations and Reform Act issues. But from a defensive-strategy perspective, it's much easier for him to cry "partisan politics" over this and win back the public by playing the martyr than if the Dems could effectively explain his substantive failiings to California voters. It's not easy. But it would be a much more stable platform from which to take him down.