Thomas Wimmer wrote
In order to prepare myself (for the written test as well as for the
whole ifr stuff generally), I would like to do some home-study before
travelling to the US.

What kind of training material would you recommend?

I would recommend you not try to prepare for both with the same
materials. The written test contains some useful stuff, but mostly
it's just a hurdle you have to overcome. Therefore, I suggest that
you use only one book to prepare for it - the test prep book by Gleim,
ASA, or whatever other outfit publishes all the questions and answers
in an organized form.

For actually using the rating, I recommend Rod Machado's Instrument
Pilot Survival Manual as an introduction, and Buck's Weather Flying as
a more advanced text.

You can also do yourself a lot of good by practicing the procedures on
Microsoft Flight Sim or equivalent product - there are lots of them,
and they are all adequate to the task.

Realize that the Mojave is EXTREMELY unlikely to offer any IFR weather
flyable in a light single. While you're there, consider hopping over
the Tehachapis and into the LA Basin, which is likely to offer you
much better weather training opportunities.

Michael