There's some basic things to remember when building a ship model...
Build your major subassemblies first, superstructure, funnel, turrets,
etc... if your deck colors (steel) are the same as the bulkhead colors
(like IJN ships for example), then go ahead and add your photoetched
rails and detail parts. If they're different, add anything that will be on
the bulkheads, but leave off the rails so you can mask and spray the
deck color.
Build all your small components, AA guns, fire
control directors, etc., and paint them accordingly. It doesn't hurt to
weather as you go either, at least a sludge wash to start with.
Paint
the hull, paint the deck, then assemble. Touching up the deck seam is a
lot easier than masking the entire thing. In most cases, your railings
will cover the seam and in some instances, act as a groove guide for
the railing.
When you work on a ship, work from the centerline
of the ship outward...this ensures you're not knocking things off the
model as you're reaching in to add a part.
And yes, since I was repeating myself from a previous thread, I cut and paste...why reinvent the wheel?
Jeff