In a reasonable world, the first step would be reforming NATO so that it becomes more neutral and focused on preventing wars rather than countering Russia. I'm saying this as a Pole, so definitely this isn't self-serving, since Poles are second most hated by Russians after Ukraine. This step should, however, happen in parallel with the EU developing its European army, to defend itself from Russia if that's needed, which is another challenging and non-obvious step, but we're closer to this now than we were before Trump.

However, we don't live in a reasonable world, so I suspect the first step will be, as much as I don't want it, World War III.