Yes, specific preparation and priming needs will depend on the surface which you intend to paint; the nature of the surface and the presence of any existing finish or treatment.
Using an undercoat will ensure full depth of colour and will seal unpainted surfaces or prepare the surface for painting.
Generally, surfaces which have a solvent based paint on already will need to be prepped and primed with the correct primer so that the water-based Eggshell adheres.
This is because the old gloss paint will form a barrier to the water-based paint.
Bare, untreated surfaces will need to be primed with the correct primer for the surface, be it metal, or wood.
Order an undercoat in the same colour as your chosen top coat to achieve the best finish possible.
If you are transitioning from a dark to a light colour, the undercoat has properties which will help obliterate the colour beneath before applying the top coat.