If you narrow the imposters down to 2 of 3 suspects (person A, B, and C) and person A accuses person B, you should almost always vote out person C.
I've ran into this scenario a few times and no one seems to understand the logic behind this move so I will explain.
Of the 3 suspects, if person A accuses person B then 1 of 2 possibilities are at play.
The first possibility is person A is telling the truth. This implies person A is innocent and the 2 imposters are person B and C.
The second possibility is person A is lying. This implies person B is innocent and the 2 imposters are person A and C.
In both scenarios person C is an imposter. It may seem like the question is to decide on voting out either person A or person B, but that would result in nothing more than a 50/50 guess as to whether person A is lying or telling the truth. However, the safest move is to always vote out person C as they are an imposter in both common scenarios.
There is technically a 3rd scenario where person A is an imposter and accuses the other imposter, however this will almost never occur as it makes seemingly no logical sense except to counter this train of thought. So unless this strat becomes mainstream, it will always be very safe to vote off person C.
I've used this strat many times and it has always worked. It isn't inherently obvious but the logic is sound.
I hope I explained this well enough. Be careful out there my fellow crew members.