which first tiling or painting

I would generally paint first but obviously not the area being tiled. If you're using an acrylic or silk paint then it's easy enough to just wipe any stray adhesive/grout off as you go along and maybe a little touch up around the edge of the tiling if needed. Painting after means covering all your tiles, especially if they're textured. Even if they're smooth and easy to scrape paint off it's almost inevitable that some will end up in the grout and this is not so easy to sort out. Best of luck, Rob

Paint after, or alternatively paint but do not paint the tiled are as adhesive will grab plaster better than paint and has less chance of peeling the paint due to the moisture in the adhesive.

Paint after

Paint first, but definitely not the areas where you want to tile. Mark the area out where you intend to tile and only overlap with paint by a very small amount. Then when tiling, just take care with the application of tiles, adhesive and grout. There is no need to get adhesive and grout all over the walls. You may just need to touch up with paint along the grouted or tiled edge but again, its not difficult to cut in with paint.