I just started my Airfix Stuka 1/24 scale. I am using Tamiya Enamel Paints. As I started painting, I realized that the paint just wasn't adhering. As I paint it looks as though I am pushing the liquid paint from one area to the next, but it isn't staying. Consulting this newsgroup, I realized that I didn't wash my kit, so I've done that. When I tried again, it was minimally improved, but I still have the same problem. Should I be doing something else? Using a spray primer maybe? Mixing up the enamel paint in some special way? Any recommendations?
What did you wash the kit with? Sometimes certain cleaners leave a residue behind that can cause adhesion problems, I normally use a mild liquid hand soap or mild dishwashing liquid, plenty of warm water, and an old toothbrush I keep for this purpose only. Let the kit airdry, or use a hairdryer on low to help it dry, don't rub it with a towel too hard, you may introduce a static charge that may cause problems.
Maybe, I normally don't use primers unless I've done a lot of putty or conversion work, or the plastic is a dark color that may bleed through, or for finishes like Alclad.
What are you thinning the paint with now?
I've never used Tamiya enamels, but most enamels are similar. I use Testors Model Master enamels almost exclusively, and I thin the flat enamels with laquer (cellulose) thinner. For the gloss enamels, I thin them with Testor's Airbrush Thinner in the glass bottle with the blue label.
To me, your problem sounds like you're spraying gloss paints, and trying to put too much on at once, the paint doesn't have time to set up, so the airstream pushes the paint out of the way. The way around this is to put on several coats, the number of coats depends on teh color and coverage, etc. For flat paints, they should dry almost as soon as they hit the model, you can almost see them dry