what's the best technique?
Tungsten tip drill bit. Go through it like butter. Tile shops all sell them, unsurprisingly..
I need to put up a new shower head and holder thing. as the other one has fallen apart. What are they called racks?
I did put in some tremendous LED lights though. They are remote controlled so in the night won doesn't have to put the proper light and have the extractor fan going on for half an hour.