There is no standard for the "blue" engine domes, as there is no official painting guides for the "fast" ship minis.
What seems to be the general consensus is that the typical Federation ships have the "as seen on tv" orange domes (some folks do red instead; more like the "pilot" version of the tv ship).
In that same mind think, the light blue color is reserved for ships using the high-power "fast" warp engines (classes such as the DDF and CF) - many folks have also extended that to the X-ships (such as the DDX and CX; none of which have official miniatures).
Those "standards" have pretty well settled in, and are used consistently by Ted Geibel and Adam Turner in their cover art CGI work.
It's really up to you what you want on your minis. The official painting guides say red domes and also red "exhaust" domes at the rear. I don't know anyone who paints their engines with red rear caps.
I go for a "tv" look on mine, with orange that has been dry-brushed with some lemon yellow:
For "fast" ships, I use the same method, but with blue dry-brushed with white:
I'll let others detail the "shiny" dome technique (since I don't do it), but my understanding is that it's clear red over a metallic gold/silver base.