New model railway wagons are just too clean to be realistic. In use on the real railway they quickly acquire a layer of sooty grime, especially in the steam era. Even if given the occasional clean, dirt still remained in the gaps between the planking and around fittings.Weathering powders, applied as a wash, or thin black acrylic paint, fill the nooks and crannies, and make the wagons look more realistic.The other major improvement is replacement of the standard N-Guage coupling, which has been used since N-Gauge started, and is an enormous lump of plastic on each end of rolling stock.There are various alternatives; I have tried several and decided to use the DG couplings. These come as brass fret containing 16 couplings, which need to be separated and bent to shape, have a loop and dropper a hook system. They are operated by either a permanent magnet or electromagnet buried under the sleepers. They are unobtrusive and permit delayed uncoupling, so a rack of wagons can be pushed over them and then left where required. If they are pulled over the magnet they do not uncouple.
In the slide show below some of the wagons in original condition still have the standard coupling. All the weathered wagons have been modified to take DG coupling. These I have fitted with only the loop on one end and the hook on the other. Initially I found that this gave more reliable coupling & uncoupling, with the only disadvantage that all rolling stock have to be the same way round - not a problem when used on the Archie’s Yard layout, provided they were initially all railed the same way round. However with the final implementation of the Rowandale layout, rolling stock will leave the goods yard one way round and eventually return the opposite way. So the full loop & hook at both ends will be required. I have found that his does just need a bit more precision in adjusting the couplings, and a compensating advantage that wagons are less likely to uncouple themselves while being pulled slowly over the magnets - I often had to add a bit of axle friction to prevent this.