Place your outside pedal (the right one if turning left) at the lowest position and really stand on that pedal with most or all of your weight. It makes cornering more secure than if you are sitting heavy on the saddle. I am not 100% sure why it works, but it does. Maybe it has something to do with the geometry of having your weight applied down low by the tire contact patch instead of three feet higher at the saddle.

But, yeah, slow down and corner with caution on wet roads. Eventually you'll find yourself cornering on a slick wet metal manhole cover that you didn't see until it was too late, and the only way to stay upright will be to momentarily interrupt your turn, coast over the manhole cover going as straight as possible, then resume your turn - and if you haven't left yourself plenty of leeway, you'll go down.