I take a plug tray, put it into a solid tray with drainage, and place that in a frame-style market pack tray. I fill the plug flat with seed starting mix and sow 1-2 seeds in each cell. I then take a second frame-style tray and invert it over the first, attaching it with 4 small zip ties to keep birds and chipmunks from disturbing the planting. The tray is then placed on an outdoor flats bench for the required cold period and germination. After the seeds are well sprouted, you can cut the zip ties and remove the protective frame. Each seedling has its own cell, so transplanting can be delayed and will be easier.
I found it very easy to cover the surface of the flat with snow to hold everything in place before putting the flats on the bench. It's much easier than trying to wet dry seed mix.
I also find it is better to mark your trays with row numbers using a silver Sharpie and to keep records in your garden notes rather than depending on tags that can get lost.