What do i thin my paint with Paint?

If it’s oil paint use white spirit and if it’s water based emulsion or acrylic use water.

The best paint thinner is water. I assume it it for a mist coat? Or their is products like Tikkurila Optiva primer that doesn't require thining

Depending on which kind of paint it's, water based thin with water and solvent or oil based with white spirit, good luck :)

It all depends if it is water base or oil base. Water base paint you just ad an extra 15-30% water to thin it as thin you want. Oil base paint you just ad a little white spirit, max 5%

Water based paint use a little water to ease it and if oil based then use a little bit of white spirit.