Small wall tiling tips

I'm needing a small back wall tiling that will also act as a splashback for a toilet/sink combi unit (I only need them to be two tiles high)

I'm completely new to this and have tried to research as much as possible but is there anything I should be aware of before starting? And any tips on the best way of doing this?

I was going to stack them vertically, so two in the center, then cut to fit ones eitherside of these.

Should I be leaving a gap at the bottom where it meets the floor for grouting? And likewise for the edge of the walls?

Thanks

Looks a good plan to me. no need to leave a gap, just silicone the joints, not grout, adjacent walls need to allow for movement.