[woodcote]

Mostly it's trying to work any gradients into the natural geometry of the track and trying not to force the issue too much. A sudden angle where two track pieces join can cause problems with grounding - depends on the car... A higher ride height and/or a sprung guide will always help.

Short track pieces certainly give a smoother gradient - same for flyovers on a 'standard' circuit. So does supporting the track - ideally with a long, continuous piece of flexible board (even cardboard) underneath.

I've never gone into bending longer pieces of tracks, although I see other people do.