I would DEFINITELY recommend using a light grey primer or a light grey paint (preferably dull or satin). Then using matt white or properly thinned down gloss white in 3-4 maybe 5 layers, of which the first two must be "clouding" the model from a little distance. I really love Gunze Sangyo's White, by the way.
In my experiments, I found out to my horror that white does not set like the other colors. Especially gloss white tends to be heterogenous and if you "insist" on a particular area, chances are it will start flowing. As a result, unless I'm looking for trouble, I really stay away from gloss white (without any primer, on a rather smooth surface).
However,if you are rather impatient or in a hurry:
A friend of mine gave me some advice on appyling Tamiya's Gloss White rather easily (but you will be risking a bottle if you are willing to try). First you apply a little primer, or a rather light coating of matt white on your model. Then, you open a "brand new" bottle of Tamiya gloss white without stirring it, put as much cellulosic thinner as it would take and then close the lid and shake it well. After that, without diluting the stuff further, you put it in your airbrush and spray it on, again in light coats. It will enable you to work rather fast as the stuff dries super quick and does not clog at all. ATTENTION: you definitely SHOULD NOT try that on other Tamiya paints, it will most possibly wreck them. Plus, your "thinned down" white will get spoilt rather easily in time.
I tried it and it works. Do I recommend? Well all I can say that TRY IT AT YOUR OWN RISK. (All you are risking is a bottle of Tamiya White by the way :-) )
If you are looking for the safe route, recommend you stick to a white with quality and be really really patient.