I took off old tiles in kitchen, and once I have removed all the old adhesive and made it pretty much even all along, I'm left with the dusty sort of plaster on the wall. Should I just pva it then once dry just tile onto it, or is it better to get some finishing plaster then tile onto that? Wall in good nick. And if I were to plaster it, will the new plaster stick properly to the old dusty plaster?

Open Question: Is just PVA enough to put on plastered wall before tiling again? for the full Yahoo Question / Answer.

As a general rule, you should prime the wall before applying tile adhesive, although some adhesives do not require certain types of surfaces to be primed. You will need to read the tile adhesive instructions to determine weather the walls need priming and if so, what type of primer should be used with that adhesive.