i don't use turn signal sitting in the left turn lane. if other drivers can't figure out I'm turning left they shouldn't be driving.
I do use signals when slowing down to turn either way, just so the guy tailgating me doesn't get more infuriated.
I signal before I start to slow down, surely that is the safest method of all?
My wife worked with a lady that never turned left, she accomplished a lefthand turn by passing where she should have turned left and then doing three righthand turns.