Have Bush drown in his own Atwater mud. The Dukakis campaign suffered from lacking a clear message (they hired and fired campaign management, and their message in commercials was confusing as a result; one on how stupid Quayle was and how the GOP was misconstrued as a GOP commercial rather than an attack ad by much of the public), and from pussy footing around when they got attacked. Dukakis ended up fighting back against the mudslinging, but far too late.
One thing to prevent is the Willie Horton/furlough attack from gaining ground. It's actually easy to do this. Firstly, the furlough program was enacted by the Dukakis' Republican predecessor. Secondly, the Reagan/Bush administration had overseen the largest national furlough program in American history. Have Dukakis fire back with that right off the bat, and Lee Atwater and George Bush will have a lot to smoke in their collective pipes. Also, avoid "Tankgate", and have Dukakis fire back at the rape question in a better way.
I started a thread on this somewhere if you need anymore info, btw.