When taxiing a taildragger across a kerb, is it best to cross straight-on or at an angle?
The rule I was always taught is to cross any 'step' - up or down - at an angle with the elevator full back:


It minimizes the chance of a prop strike, which is much more expensive than a wingtip strike
When going 'up', you avoid having both wheels up against the step at the same time, which usually means you need a burst of power to get over it, which could lead to sudden acceleration and sharp braking
When going 'down' you avoid the aircraft dropping down suddenly, with the same risks of strikes or an increase in speed
Lifting the elevator reduces the chance of it striking


There may be some differences for specific aircraft types, but I've always followed that advice and never had a problem. I've also never seen an aircraft get close to a wingtip strike doing this, but I suppose it could happen if the step is large enough. Although in that case you might want to just find another taxi route.