Use a proper acrylic based tiling primer sucha s bal prime apd or ardex p51.
Sealing plaster walls before tiling.
New plaster work should be fully dried before tiling work is commenced this drying time varies upon temperatures but can take up to 4 weeks before fully cured.
Also now it s been plastered you will be restricting yourself to a tile with a max weight of about 16 kg m2.
Pva is not suitable for tiling for various reasons and this has been debated many times here in the forum.
Sand with a medium grit sandpaper to create a uniform surface that s not too smooth.
Otherwise a few complications might occur.
If you choose a heavier tile you will need to overboard with a backaboard.
I did question the rep about this and he was adamant that new plaster should be pva d because if not the plaster sucks the moisture from the adhesive too quickly therefore it doesn t set properly.
When applying tile to a plastered surface it is important not to overload the weight of what the plaster will take before failure occurs plaster will support about 20kg m2 or about a 9mm thickness of ceramic tile.
Before you get to it you should level the bathroom the kitchen and or the hallway walls.
Also keep the walls you are about to tile free of moisture dust and grease.
Seal the walls with a skim coat and let it dry thoroughly.
Thoroughly vacuum the area and give the wall a once over with a damp sponge or cleaning cloth.
You want the tile adhesive to have something to grab onto.
Adhesive grout and tile 20kg max weight onto plaster.
Don t use paint glue pva wall paper paste only use the primer recommended by the adhesive manufacturer of your chosen tile adhesive.
This way the adhesive will stick properly and last in the long run if you are using a good product.