These are great for giving as a gift bag. People can reuse it, so its a gift in and of itself. I find two matching fabrics, they don't have to be Christmas fabric. I then cut 3 inch strips to make the straps. The strap length is a person preference, as is one or two staps. For me I just cut the width of the fabric, which is usually 45 inches, out of both the fabrics, and make two straps. Sew the straps with the good sides facing each other. Turn it inside out, iron it down, and top stitch the straps, which is sewing a line on each side of the edge of the strap as close to the edge as possible without going over the edge.
Then I take and cut a huge rectangle out of the remaining fabric. Usually about a 18x 24 size bag, but your demonsions can vary, just as long as it fits what you want to put in it. You can simple measure the size of the gift, add a couple inches to each side, and double the length.
Turn the good sides towards each other, and pin the handles in place. Remember they will be on the inside of the fabric during pinning. Sew the two tops, then turn it inside out and top stitch the tops. Finally, sew the sides together. Its super easy, cute, and functional.