Only paint completed (sub-)assemblies

As a kid, I built every model in the same order :

1. Paint everything while it's still attached to the sprue
2. Glue everything together
3. Apply decals

Some building instructions suggest pre-painting all parts on the sprue, and that is what I always did. While this has its advantage of easy access to all nooks and crannies and it gives you something to hold, disadvantages are :

• after removing sprue attachment points, you'll need to touch up the paint
• paint will cover areas where glue needs to be applied

From past experience, gluing (small) parts on top of an already painted surface yields bad results. Scraping paint off a flat surface to attach an antenna or some other detail isn't always possible. Many of my older models (see : Attic) had parts (wingflaps, landing gear doors, antennas, ...) fallen off, because they were glued on top of gloss paint and the bond didn't hold. Had I glued BEFORE painting, the bond would probably have been strong enough to survive long-term storage.

So, what I do now, is try to finish construction as completely as possible before starting to paint (example), yielding the best possible bonding between all parts.

Complex shapes call for painting of sub-assemblies, where painting the completed model would be difficult.

Above are the sub-assemblies for the saucer and drive section of the Enterprise. I think its pretty obvious that gluing them together will make it more difficult to paint certain areas.

I haven't assembled the engine nacelles yet, since they contain clear parts that need to be painted on the inside. (obviously one of the exceptions to my assemble-before-painting rule).