What could Clinton and Bush have done to prevent 9/11?

I'm putting together a little piece on how 9/11 could have been preventable. If anyone has any information on how Clinton or Bush could have taken more action to help stop 9/11(e.g. Bush not ignoring memos and Clinton taking action after first bombing) I would greatly appriciate it. Also, if you know anyone else who could of contributed to the prevention of 9/11, that would be good, too. Thanks