I usually don't engage.

I've had a few people say "sorry" when they cut me off. Hopefully they'll be looking the next time.

However, after a close call, I try to evaluate what I could have done to make my ride safer. Sometimes it is nothing. However, it might be to slow down when you're approaching a car coming towards you from the right, or to move left and prepare to brake.

Oh, and be careful passing cars on the right (and I suppose getting passed by cars).

Turn lanes can be tricky, and often means moving left and either taking a lane, or splitting lanes.

Anyway, take charge. Don't live life depending on others keeping you safe.