"I met him for 30 seconds in 2012." - Paul Ryan
According to Patrick Healy in the New York Times, during the presidential debates this fall, Mr Trump will try to throw her husband's infidelities in her face to humiliate her, saying that she enabled him by staying with him (this is a strategy that can easily backfire because Donald has had his share of extra-marital affairs), she is responsible for the security lapses at Benghazi, Libya, and finally, that she has been a corrupt politician all along.
These debates could easily devolve into a nasty game of He Said/She Said that Donald's campaign is hoping the results will lower Hillary's favorable ratings in the innumerable polls. I think her best strategy for this is to assume the role of a mother dealing with her out of control son. It's clear that Donald never had the parental supervision to set boundaries when he was a child, so she should come to the first debate prepared with a few props.
Each time that Donald utters one of his nasty comments or lies, she should reach into her lectern and pull out a bar of soap, walk over to Donald and place it on his lectern, with the admonishment that he is going to wash his mouth out with soap until he learns to behave better... It's not at the level that Elizabeth Warren attacked Donald and made him back down, but it might be just as effective.
Then again, I am relishing the Twitter war that could emerge the first time Donald calls Vladimir Putin a loser, who looks better with his shirt on...