hello

good question!
my suggestion for left turns....you always generally "act like a car" in the way you move or the timing you use. you generally always do this with two or more riders but you can get away with more things if you're by yourself.
but the main objective is to make sure the vehicles around you 1) know you're there and 2) know which way you're going. you generally don't get too many buttheads that won't ever let you go. most people are either overly polite or treat you like another car.
if you're fearful or nervous about turning then the best thing to do is be overtly obvious about where you're going. move over earlier than you probably would which enables more cars to see you sooner and see where you're going. this way you won't have as many fears that they don't know what's going on.
also, if a car waves you on to go or waits for you, always make it a point to just put a hand up as a thank you. i always try to be as polite as possible every time i'm on the road.
it makes drivers happier and helps giving a nice first impression for someone who's never driven past a cyclist before. it's also important because it lets them know if what they did was good or not for the cyclist.
if you're making a left in the middle of the road you're on (i.e. not at an interection): wait until traffic coming up behind you ends or there's a break, point your left arm out to signal you're going left, and move into the lane or near the yellow lines and turn when oncoming traffic is clear.
if you're making a left at a stop sign or light with no left turn lane: you act like a car whether there's one lane or two. if there's two, get in the left-most lane. if you're in a line of cars stopped, it's usually better to act like a car (or motorcycle for that matter) and take up a space in the line of cars.
if you're making a left at a stop sign or light with a left turn lane: whether there's no cars or a line of cars, i generally ride up to the front line and wait on the right-side of the left turn lane (i.e. at the first car's front passenger side). it makes it easier for everyone, especially yourself. when the light or arrow turns green then you just pick your turning line so that the cars pass by you on your left and everybody wins. haha