Would piecing opposing sides first (say right side rectangle, then left side rectangle) then adding your top and bottom rectangle help? This way no partial seams.
For first paper piecing projects, I would not suggest any patterns that call for partial seams or attaching of multiple pieces to make one block (part A, part B, part C, etc.). The easier the pattern, the better, until you have mastered the pp technique.
Hope my suggestions help! Without seeing the actual pattern, it is kind of difficult for me to picture it.