This was my second Charlie bag . I added 1/2" double folded bias strips to the handles, I lined the bag but used French Seams to keep it looking neat. Also, on the bottom I "squared" it up some and created a flatter bottom, instead of the folded bottom that the instructions advise.
When making the little bag on the inside, I used 1/4" seams to construct the small bag in order to have a little bit more room when I folded the larger grocery bag into it....It helped alot.

thick cotton