When I built my Audi Quattro rally (2 colours yellow over white) I sprayed the whole car with the white first and left this to dry for a week.Then I masked out for the yellow sections using Tamiya masking tape.After spraying the yellow I left it for about 20 mins before carefully removing the masking tape.This method worked fine for me and none of the edges lifted on the yellow as the paint was still flexible after 20 mins drying but not too soft as to make rough edges.I was using Tamiya TS sprays for the white and yellow.Hope this helps,it's the way I did it but probably not the only way to do it.Experimenting is the key to success and see which method works best for you.Practice on an old model shell to perfect the technique before you commit it to your model.