How to sharpen Secateurs

It generally requires some training and experience to do it freehand but you can buy special sharpeners for them. They're pre-angled and you just slide the blade through the sharpener.

 

As I have different sharpening stones to hand I use whatever one I think is suitable and how fine an edge I want. I have a carborundum for rougher work, and two different types for finer work - an oil stone and a water stone. There's an argument that you don't need to use oil on a stone but it depends on how precise an edge you want to get - but I'm old fashioned