Trace your stocking on a paper bag, grocery size, (if you can find one!) or use brown kraft paper. Use pencil for tracing as you don’t want any ink to get on the stocking. On paper pattern add 5/8" all around for your seam. Add more (1 1/2 to 2 inches) to the top as you will be folding over the lining to sew to the top of the stocking. Cut out the pattern, pin to lining fabric (I’d use medium weight lining fabric…shiny fabric), cut 2 pieces of fabric, then sew a 5/8" seam, except for top. Put the lining as is into stocking (wrong side of lining to wrong side of stocking), adjust to fit into toe, etc., fold fabric lining at top to inside (right side of lining to wrong side of lining) and using small stitches sew to top of stocking. If you’re brave you could machine sew the lining to the stocking; otherwise, use a lot of small hand stitches and avoid anything too heavy in the stocking. I made quilted stockings for my children and instead of hanging them when full would put them on the floor next to their gifts to avoid stress on the hanging loops.
If you have any questions feel free to ask. I’m so used to doing things like this and may overlook something in the telling.
Hope this is what you meant by “Any ideas?”