I had checked out from the public library a book about stitching and patchwork and repair of clothes, which I have to return soon, and then remembered a book I had bought about embroidery and embellishment on clothes. Below are the jeans I wore to the ceramics studio and another pair I wore to work after I finished running stitches on them.
Both books came in handy. I trimmed the frayed denim off and then cut a patch from a pair of jeans a neighbor gave me. The most difficult part of patching I think is the safety pinning of the patch to cover the hole, made all the more difficult if if you don't take out the inseams because you then have to stick your hands into either end of the pant legs to pin all around the patch.
My whip stitches were not the most elegant, and my friend's jeans had deliberately been frayed. However, I think she was pleased by the tiny crosses I had stitched over these two holes.