What tools/methods have you found the most helpful?
Before my B2 exam, I used Bing AI a lot, to find what phrases are more common in German that the others. For example, when you want to ask if a seat is free, there are multiple options that are different in friendliness, etc.
Other than that, Bing AI is also a really good Gesprächspartner. You can explicitly tell Bing AI to use easier or more difficult German, which is useful.