“Jack of the old blow” – how to tame?

I drive an old BMW 528i, model E28. – I have noticed several times that the car likes to oversteer and then also very suddenly tends to oversteer. Last weekend, for example, I had produced a slight drift on a motorway driveway (curve, wet, 2nd gear, a good 3’000 rpm, acceleration) in the rain unintentionally. So far so good, I think, with the driving characteristics of the old rear slings, which are usually very good-natured and pleasant, I will have to live and k The question is simple, how do I react correctly, if the rear wants to overtake the rest of the car again?