Split Slate Bathroom tiles - Any advice?

Hi all

Just forked out a mini fortune on some slate bathroom tiles. Was initially planning on getting a tiler to do this for me, but have bitten the bullet and now plan do do these myself.

I have tiled a few rooms in the past and always done a decent job IMO. I am an ex Joiner in a previous life, so know my way around DIY.

I am just curious what extra steps / tools / prep etc i will need to get these things looking good?

From first look, there is no grouting?

If so what is the best way of waterproofing for the shower cubicle?

Any tips very much appreciated