Primer

Most people assemble the majority of the model before priming. Priming does several things for you - makes any rough or unfinished areas easier to see for correction, helps to seal any puttied areas and gives you a good base for your color coats.

Either color of primer will work but it seems that lighter colors seem to be brighter if applied over white primer so I would probably go with the white primer for this project. If the project were to have white as the final scheme, I would probably go with grey primer because it makes it easier to spot any areas that I have missed.

Hey RODC,

I've never heard of priming before beginning assembly. At least not the whole model, however I do primer the joint areas on subassemblies to make sure that my joint lines are filled.

Regarding a primer color for a yellow finish, I think the general concensus here is that white is best, and apply the yellow in several light coats until you get the depth of color you want. I've found that Floquil's Reefer White (flat) makes an excellent primer and it sprays and covers very well.
BTW, which brand and type (enamel, acrylic, etc.) yellow are you intending to use?

stinger

You'll have to put on a white primer as the guys have said, or you'll never get a decent finish on the yellow.

I learnt this the hard way

Best of luck

Karl

Thanks guys....I knew I could count on the collective knowledge from the Board. As for the yellow I will use, I am still undecided as to the final shade of yellow but will be a Testors Model Master enamel.