The first time I did the car and a few other cars I have done in the past, I taped right over the base. If you give the base some time to dry it's usually ok but the ones I did were solid colors. I did not want to risk messing up the metallic.
The consensus on here,because I layed down white with a pearl intercoat,was to paint and clear the car,then lay out the stripes. It worked great and a nice feature to doing it that way is if you have bleeds or overspray,you can wipe it off the primary color without hurting it. I used SPI reducer on the corner of a paper towel and carefully cleaned up the edges of the white with my thumbnail. There were just a few small spots but it worked great.