How to tile a part painted wall

[LondonPro83]

Hi there

I'm looking for some advice on how to part tile a painted wall. It's a kitchen splashback from the counter halfway up the way just below a shelf. My question is, prepping the surface for tile causes a bit of a mess - is it easy enough to prevent this from messing up the rest of the paint which is staying put. Will grouting etc make a mess too? And whats the best way to finish the last row of tiles as they won't be meeting the edge of the wall. So many questions! Hope that's clear enough.

Many thanks

 

[Bond]

Mask off the area out with the proposed tiled area.
Apply a bead of decorators caulk to edge of tile and paint in.