How do you think one should prepare? Is there really anything different we should be doing, then what we are most likely already doing?
No, any one of us could drop dead at any second, but these prophecies were given us so that we would not lose heart and despair. In fact, in the lecture series by Bishop Williamson I posted on the other thread (parts of it), he indicates that the message is that "in the end, God wins", to give us hope and to hearten us. So, if we see a Great Apostasy and falling away and this imposter pretending to be Christ, don't fall for it, that it's not He. If you are tempted to lose the faith because the Church has appeared to defect, hang in there, since it had to happen and was allowed to happen, and is not what it seems.
THAT is why we were given this Revelation and many private revelations as well, including Fatima.