(Completely armchair economist here)
Quantitative easing was the right policy at the time, but should have been supplemented by a major regulation push and protection of the individual debtors.
Serious Glass-Steagal regulations should have been put into place and banks and financial firms reigned in, both in Europe and in the USA.
US Dollar supply should have been allowed to go slowly done once situation was a bit more stable.
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko