Firstly I bought these yellow invisible plate hangers from John Lewis, they come in different sizes, about £1.50 for the smaller ones so not too pricey....
Give all your plates a good clean, and then lay them out bottoms up. The instructions with the plate hangers says to rub some scouring paste on the back of the plates - I just made a paste using baking soda, a little water and a little salt. Rub this into your plates, rinse clean and leave to dry.
measure up your plate hangers, I found that mostly they overhung the flat part of the bottom of the plate, so I trimmed them all down so they fitted neatly into the flat part.
Then with your fingers, rub some water into the sticky side of the plate hangers until they are gummy, and then stick them to the back of your plates.
Then you need to leave them overnight to dry. Don't worry it is possible to remove the plate hangers at a later date - you just need to soak the plate in warm water, and it will not damage the plate.
Finally, lay out how you want to arrange the plates, and then dig out your hammer & nails!
I started hanging the ones from the bottom first, so they don't end up too low on the wall which would look at little weird. I also found it best to hang the plates as you go along rather than trying to mark out where your nails are going first, so then you can work out spacing as you work. While I stuck to my layout plan, you don't need to be massively accurate.
My favourite plate from the display is the one from Mud Puppy at Etsy, which was a lovely Christmas pressie from my other half....! Its simple but so pretty!