Do i need plastering on normal plaster board before i tiled?

No straight onto plasterboard is just fine

No

No, in actual fact plasterboard will hold approx 32kg per square m whereas plaster skim will only hold 20kg per square m so it's better to tile to plasterboard than skim. Saying that, you should not tile direct to plasterboard in the shower area or wet area if it is a wet room. Ideally you would use cement fibre board in those areas (which can hold up to 200kg/sqm depending on brand), and waterproof the substrate effectively using one of the many tanking solutions on the market.

If it’s around a shower cubicle then ensure moisture boards are used normally they are the green ones a few times we have skimmed all the walls before tiling but it is fine to tile directly in to plasterboard so you shouldn’t have any problems at all

Prime the plasterboard with a correct tiling primer, then tile straight on to the plasterboard, the plasterboard can hold more weight than a 2 to 3 mm skim coat. Visualise the plasterboard is mechanically fixed and the skim coat is stuck. Tiling to something mechanically fixed is better than tiling onto skim and the same goes for paint. Hope this was helpful