In US Air Force service? Those were usually bare aluminium, as far as I know, which means that using a single colour will look unrealistic. What you want to do is paint different panels in different shades of metallic, to give minor differences in colour between the panels. I found this fairly easy (if somewhat laborious) to do by mixing a small amount of a different colour into the metallic paint — for example, a touch of medium grey to make it a little duller. Apply this to different panels at random, then add maybe a just bit of blue to alter the tone again and also paint random panels in that, and repeat as necessary. After a while, start with some fresh metallic paint. The trick is not to make the difference in colour very great, but just enough that you can see it.
Also, I’ve observed that in the real world, panels on aircraft tend to display the same colours symmetrically. That is to say, if a certain panel on the left wing is darker than those around it, then that same panel on the right wing is likely to also be darker. I suppose this may be because those kinds of panels are made in the same factory at about the same time, but I could be wrong