It will depend on the finish you are trying to achieve. If you are going to do a nice clean or very lightly weathered a/c you may want to use the polished aluminum. That and the chrome need the gloss black primer. Bear in mind that these will be VERY shiny. If you are going to do a more heavily weathered bird... a combo of the different "regular" colors can be used. This can be used over many different primers. In a webinar that was given last week on this subject, the presenters used several different primer. But the one of the common techniques they all used was to work the primer after is applied. By that I mean they will go it with very fine micro mesh clothes, to give it an extremely smooth surface. The even said they had applied it over bare plastic but only after sanding the entire airframe down with micro mesh. But in general they all preferred the use of primer of some kind. Future can be used as well. I have had very good results with Model Master Gloss lacquer.
If you start with and overall aluminum then mask of different panels and apply some dark aluminum, duraluminum etc. Don't over do it or you will get too much of a patchwork look.
And very nice effect was achieved by using a regular primer, then masking of some panels and applying some gloss black to several panels. The model was then given a coat of aluminum and the different undercoats gave some very different looks to the single color of Alclad. Play around on some sheet styrene to get the effect you want.
This one was MM gloss lacquer base then overall duralumin and some panels with aluminum and dark aluminum.
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