Best ratio of paint to water for a 'mist' coat

[fallingdan]

As this is my first post, hello everyone. I thought I'd start with a simple question. I have a feeling I made a bit of an error painting a freshly skimmed (dry, obviously) ceiling when the paint began to peel off in some areas. I now know that I should have applied a mist coat to begin with but what are the correct proportions of water to paint?

Thanks in advance

 

[PrenticeBoyofDerry]

Depends on the quality of the paint, a good quality contract paint would need about 15%-20% water added. Poor quality paint less, as they are already watered down.