pre-IFR training/preparation?

I will be starting IFR training soon and would like to minimize the pain /
maximize my learning potential.

Is there anything that recent (or not-so-recent) IFR students wish you
had done in preparation for training? (specific books to read, home
flight simulator)

A friend has invited me to tag along in the back seat during his lessons
and I have learned a great deal following along while looking at the
approach charts... I have found it an excellent way to become familiar
with alot of the terminology.

Thanks,