Yes! Not sure which way to go? Just always go upwards. When it hits the top of the slingshot or inlane/outlane divider, don't let it decide which way to fall...shove into the ball to bounce it back up towards the top of the playfield.

I think a lot of people incorrectly think that the goal with nudging is to move the ball. It isn't. (There isn't enough friction between the playfield and the ball to make much of a difference.) The goal is to move something into the existing path of the ball to redirect it.

Example: you can tell the ball is heading directly into the outlane. Usually, the best thing to attempt is to move the inlane/outlane divider (which on many modern games has a small round rubber at the top) up and out...into the direct path of the ball. Now, instead of going straight into the outlane, it will hit hopefully the post and head in a different direction.

If the ball is coming STDM, you can attempt a slide save. (I wouldn't necessarily call this nudging, but it does involve moving the machine). The ball is going to continue on the same trajectory regardless of what you do, so your goal is to slide the machine to the side enough that the tip of a flipper has now moved into the path of the ball. (You probably want to flip as you are doing this, so that the flipper is horizontal at the moment that it intersects with the ball...which gives you the furthest "reach").