I did quite a bit of searching on here recently for this exact topic. The conclusion I found from a few posts of random threads by experienced members, was to deglaze & rough the discs with some fine wet & dry, emery, brass wire wheel or something similar, so that there was some surface texture, but definitely not too rough.
I went with the brass wire wheel, ended up with a brushed steel kinda finish on the discs, hoping that's the right way.