Start by confirming which assessment your office is using, because Bain's testing format can differ by geography and recruiting cycle.

Practice the format you will actually face: numerical reasoning, logic, data interpretation, or other tested modules. Familiarity with timing and interface matters almost as much as raw aptitude.

Do a short diagnostic first, then spend most of your time on the question types where you are slow or inconsistent instead of repeating sections you already handle well.

Figure out the exact test first. I wasted time prepping the wrong format.

Timed practice was the biggest thing for me.