Honestly, I have tried sharpening knives and hedge shears and it is easier to take them to a knife/ scissor sharpener who has the best tools.
If they are a $20 bunnings pair, follow this DIY
https://www.instructables.com/Sharpen-Hedge-Shears-with-a-File/If they are $200 Fiskars or wolf-graten shears, I would have them professionally restored back to an edge, then keep up maintenace with an ezilap
https://www.amazon.com.au/EZE-LAP-P...ZC?th=1&psc=1&smid=ANEGB3WVEVKZBJust like a cylinder mower - which you have ground back professionally every few years then maintain in between with a back lap.