Placement of a dress pattern from old dress

So this week, I have a sleeveless dress that fits perfectly, but looks tatty from over use.

I've carefully unpicked the stitching and have cut the front down the middle, I've unpicked the darts and marked the ends and the widest points with red tacking threads.  I've just bar tacked these points.

Now to lay them out onto fabric

What I've done here is to lay the centre of the front piece along the fold and the back piece next to it.

It's easy enough to lay the front piece straight, if you have unstitched well and cut the dress straight.  

The back piece is a bit more tricky.  Lay the back piece as straight as you can beside the front piece.  Measure the ends of the darts to an equal distance to the selvedge.  I've marked this with a white chalk line in the photo.

You could go a stretch further before hand by marking a chalk line along the length of the back piece with the dart ends giving you 2 points of the dress piece and measure along this line to the selvedge to ensure a better straight of grain.

Use carbon tracing paper and wheel to mark in the darts and the zip end point.