I like to fill up with water first to about 750-800ml and then put 150ml of soap in after. Mix gently but thoroughly before putting the bottle on the hardware. Then you’ll have to play around with the dials a bit. I typically start with the fan wide open, and +/- all the way to +. Then I’ll adjust down from there till I get good foam. Kranzle’s and higher output pressure washers don’t usually need as much fiddling around which is why Matt typically leaves it at full +.