RE: Painting yellow strips over blue basecoat
Yellow and red are the worst colors to try and put over a non white base coat. You can put yellow over the blue but it will never cover to show the true yellow. You will be much further ahead if you put on a couple of coats of white before you put the yellow down. In the future, always put your lighter colors on first, preferably a white base coat, then yellows and reds and then mask for the darker colors.