The alterations I made on this first wearable muslin... I simply took in the rear seam a bit to make the back side a little less round... my hips are narrow and my rear end could be classified as "flattish". For my second version of these shorts I'll make a small Flat Butt Adjustment (yes, that's really what it's called).
Here's a pic of me styling the shorts with my Little Birds tank.
Cost: Nothing, this was made from an old curtain that had a hole in it.
Time: 4 hours
Note to Self: On the next pair, add a little more fabric to the hem allowance, so the hem doesn't pucker.