What preparations do humans need to make to immigrate to Mars?

This is a difficult question to answer. In theory, as long as there is enough time, human beings can have perseverance, and one day they can. But the reality is that it will take at least 50 years for the fastest spacecraft (the kind that no one has) to reach Mars from Earth. If people really need to immigrate to the past, we need to develop living freezing technology first.