I totally agree with the Tamiya Fine White primer as a good starter for any light color paint overcoat.
Another need is to then "polish" that primer coat a bit. It usually has a very "baby powder smooth" finish when correctly applied, but I recommend using either a very fine (1000grit or higher) sand paper, or very coarse paper towel (if no fine sand paper is at hand), in order to have a nearly glass smooth surface to apply your gloss paint to.
In my experience, as nice as the TFWP is, it's a "dull white", and not a bright white color, which is what you need for an airliner. If you normally use enamels or lacquers, I recommend Model Master Gloss White, thinned with lacquer thinner, and misted on in a few fine coats. It's a much brighter white, which I believe you'll see as soon as you apply it over the primer white finish. Decals can be applied directly over the gloss white, and then you can then apply the clear gloss of your choice to seal them and add a bit more shine.
Others who use acrylics can recommend a good acrylic gloss white to use, but the point I'm trying to drive home is that as nice as the Tamiya Fine White primer is, it is not as bright a white as a gloss white paint, especially for airliner liveries. Hope this helps!
GIL