body line help

Do it like he says. Make sure you skip a section in the middle. Don't do 2 adjacent sections together. Get the 2 surrounding surfaces right 1st then do the 1 in between. In your case I'd probably do the top section 1st & then drop to the lower middle section next. Then go back & do the top middle section. Use the harder filler for the outer sections & then use the polyester filler(glaze) for the middle. Polyester filler sands easier & should help you not to cut into the work you just did on the other sections.

AdamR's instructions & CUUDAK's are very good too. His pics are what you should end up with.
Good luck & be patient! Show us how you make out.