I use u shaped shorting pieces from n.s. wire, I got a coil from ebay very cheap. Think I cut bits of plastic away from between the sleepers to make it easier. Important though to wash the point under the tap after you have finished to get ride of the flux that will go green if not removed.
When using dcc isolating sections aren’t used so you can end up with many lengths of rail, so I like to have at least a dropper at each end so I’m not dependent on the fishplates. It’s also a good idea to mark the track and points on the underside as you can end up with lots of droppers. Instead of soldering across the fishplates I put L shaped n.s. wire droppers and pick these up from underneath. Use thin wire and drop it at the point of pivot or the switch rail may twist. It only takes a few minutes and you don’t have to worry about painting the track.
Hope this helps
Phillip