Try to get the wand resting in the spout, nozzle at about where the tip of the hour hand would be on a clock at about 9:15. I use Oatly Barista and when I shake the carton before pouring, I get some residual bubbles on the milk surface. Seeing these spin initially helps indicate the wand is in the right place for the whirlpool effect.
I’m not sure I ever really ‘plunge’ the wand either, I just keep listening for the little rips until my hand gets hot, seems to work fine. Obviously if the milk has stretched to the point of overflowing then plunge…
I like to give the espresso a good swirl before pouring to combine the crema a bit.
I would say the machine makes a difference also. I’m not sure I ever really got a satisfactory microfoam in years of Silvia ownership (although it’s totally possible so it was my technique) whereas with the Bianca I barely have to wave the jug in the general direction of the steam wand and I get a decent foam.