For a quick, basic, lined bag, with a feature fabric on one side and strips of prints on the other, this is what I do:
1. Cut one panel of 16" x 18"
2. Cut 16" length strips of even width, or mixed widths depending on the effect I wish to create, eg between 1.5"-4", cutting enough to make a 16" x 18" panel when sewn together.
3. Layer each panel with batting (and a muslin backing if wish) and quilt as you like.
4. Trim both panels to 15" x 17". Place right sides together and stitch 1/4" or 1/2" seam around the sides and bottom.
5. Make a gusset so the bag has a flat base: flatten the sides of the bag so that the side seam rests against the base seam and form a triangle. Sew 1 and 1/4" across the point (I usually do it three times) then trim the point off. Repeat on other seam.
6. Cut lining fabric 17.5" x 15.5" (two pieces or cut on the fold). With right sides together, sew the side seams and bottom, leaving a four inch gap in the bottom for turning the bag later.
7. Make a gusset in the lining, as in steps 5 and 6.
8. Make handles for the bag, choose desired length - mine is usually about 28" (pre-sewing). For two-colour handles: cut two strips of each colour, 2.5" x 28". Press a 1/4" fold along the length of both sides, of each strip.
9. Cut batting of 1.5" x 28". Wrap first colour around the batting, then layer other colour on top to make a sandwich. Sew 1/8" along each edge (or closer if possible) and also sew a strip right down the middle of each handle.
10. Attach handles to the outside of the bag and pin in place, keeping the pins away from the upper edge). Stitch 1/4" from the top edge, triple stitching for reinforcing.
11. Insert the bag outer into the lining so that the right sides are together and the handles are tucked down out of the way. Stitch 1/4" around the top, reinforcing over the handles and side seams.
12. Carefully pull the quilted bag through from the inside by using the gap in the base of the lining. Fold the top down and slip-stitch the gap closed.
13. Top stitch around the upper hem of the bag, holding handles up out of the way.
The bag is finished, remember to date/label it somewhere!
