As well as painting I've also experience in racing tourers, with the shells where the paint is chipping away is that on the nose of the shell?? They are subject to a lot of hammer there...
What I tend to do when prepping a shell, I first scour the inside with wire wool to provide a key for the paint (if using chrome paint don't do this in the areas you are painting it with as the effect diminishes) wash it down in soapy water, and once dry I go over the inside with a piece of kitchen towel soaked in lighter fluid to remove any residue left over.
When putting the paint down mist each colour in light coats & allow to dry completely before you put further coats down.
Yep check out Jon Millers RCS site as mentioned, for both tutorials and he sells everything paint related for these shells
