Yesterday I made a pretty good bag. This isn't a tutorial, but I'll share some aspects of how I made it and how it turned out. Eventually, I will be superior at interfacing and corners, then I can improve with visual details, as well.
I put together fourteen squares of Moda Modern Background Paper Newsprint, and then cut fabric from a larger piece to match.
I put the inside out newsprint bag into the other one, and sewed them together. This is where you can insert a tab for a button closure, or fasteners or hooks for a detachable strap, or the ends of straps themselves. You leave an opening at the top to invert the bags so they are now reversible, then sew across the top to close them.
I inserted my button loop while sewing the bags together, and then sewed a decorative stitch around the top, but inserted the little hooks for a strap (a thrift store necklace) afterwards. Also, I hand sewed trim to the outsides of the bags, and that should have been done first, however, it was kind of an afterthought.
And so here's how it looks all finished.