I think we will put this one down to experience. My first attempt at sewing from one of my vintage patterns, Simplicity 6392 that I posted about here. The only changes I made to the pattern were to shorten the skirt and remove the strap across the back. The construction went quite well except that despite using all the same seam allowances the skirt did not fit the bodice so I had to un pick the skirt side seams and redo them but everything looks pretty neat and well made, even the pleats which were my first ever try with the technique. Problem is that is doesn't fit very well. It was always going to be quite a loose fit as it is a pull over dress, but I just don't think that the style really suits me. I like to emphasise my waist. If I weren't such a lazy and impatient sewer I would have tried to fix this problem when it first became apparent, after I had cut out the pieces and pinned them to my dress form. I would have added darts and a zipper, but I am lazy and impatient so I decided to sew the pattern as is and see what I ended up with. What I ended up with was a pretty much a dark green sack with a low back that I can't see myself wearing beyond hot summer days when I'm not planning on leaving the house. Well anyway here's a load of pictures that don't really do it's badness justice.
I can't decide if adding a waist belt improves matters or if there is just too much fabric in the dress and/or it is too short to make it work.