Sometimes I use a solid piece of printed fabric and other times I use "quilt" patterns. I rarely use just plain fabric. For myself I only use fabric that matches the occassion--birthday, Hanukkah/Christmas, Passover/Easter, anniversary is usually a pair of wedding rings, etc.
I have never used an actual pattern but I do cut the paper as on a fold at the bottom. My small bags are 7" square when completed. I first hem 1/2 inch all around by doing a true hem (folded and the folded again) so all rough areas will be covered by the hem. I pin the square on the opposite two sides with the folded side at the bottom. I do not sew on the fold. Then I sew both sides. You can then add ribbon or bias tape to hold the cording to tie the bag closed. One time I used snaps to close the bag as it was for a 3-year old that loved to pull snaps apart. Or you can close it with a fabric tied around the neck of the bsg eith s ribbon snd "fancy" bow.
The larger bag is worked the same way only the dimensions are bigger to fit your gift.