it will be very difficult to get a 7/10 coolmini rating on yellows starting with primed white. it can be done, but strangely enough that would be harder that starting with black. IF you're concerned with the result, and you say you are, this is how I get my IP:
1. spray black.
2. Darksun Foundation (either leave black exposed in cracks in armor, or go back and line in - either way expect a bit of touch ups)
3. apply a layer of mixed Darksun and sunburst yellow, I'm not sure of the exact ratio but its something like 50/50 or 25/75 (75 being sunburst, obviously).
4. Apply multiple thin layers of sunburst. This part is annoying and over time you'll get a feel for it/develop your own shortcuts. You'll know you're done with you have solid, solid yellows.
5. Apply touch ups. If you left the black exposed, chances are you'll have to go back and touch up a few cracks in the armor, if you black lined-in then you'll likely have to touch up the yellows around the lines.
5. highlights. I do one layer of badmoon followed by skullwhite. don't be afraid to be bold here, so while it's still best (as always) to watch the thickness of the lines and make sure they're properly thin, don't worry about the thickness of the paint. Actually, i use a thickened up badmoon to make sure it really gets on there and don't water the white down at all as one typically would.
6. at this point, you'll be saying "wow, that's really bright." it is. too bright. apply a sepia wash. this is a bit trickier than it souns: the point here is to A) simulate a bit of light weathering, but more importantly to b) darken that yellow down, giving it even a TINT of brownish that adds depth. Here, I usually do 2 thinish to mediumish washes until i'm happy with it. but, again, you'll have to figure out what works for you, so I'd recommend start with multiple VERY thin applications. be careful not to overdo! this also blends in the highlights perfectly.
if you want to know how to do the weathering, its pretty simple and I could give a short how-to. hope that helps!