I agree with the white thingy. I have found if you put a very light coat down first, let it almost dry, or even dry for that matter, then additional light coats till it is covered works best. White requires much patience. If you are doing Gloss white, first put down a coat of matt or flat as an undercoat.
Now here is a photo of 07 which I found on the internet, where are you looking at putting down more black??? Am I overlooking something?
If it is a stripe, above is the way to do it. Trim a piece of Tamiya tape the width, or shape you want and mask either side of it. Pull that to size or shape tape off and paint. Easy peasy. Best way tho is to put down the strip color, put down the trimmed tape over this, then mask each side a you need to paint each color each side. then pull that tape when all the painting is done.
Keep strggling mate, we all do it.