I use a lot of (other-than-single-digit) hand signals to let cars know that I know they are there and that I am paying attention. if I am coming to a blind curve and take the lane, I will signal "slow" and maybe even move further left if I see a car coming so the car behind figures out that I am looking ahead .... and when I pull to the side to allow a pass, I make a windmill with my arm, saying "Pass me now, please." Since I often ride the same roads it is not impossible that I will meet the same drivers ... but in any case, communication changes me from "that idiot on a bicycle blocking my way" to ....
"that idiot on a bicycle blocking my way and waving his arms like an idiot."