I am often asked by non-sewing people, how to sew on a patch. I sew on iron-on patches too, because I am suspisious that way. I generally match the top and bottom thread to the patch background color. I use a long machine stitch if I might need to remove the patches later.
The 759 were originally on his blue cub uniform. They
were sewn on using a rectangle (see back, below).
The patches below were tricky because they are on a pocket. I hand sewed those in a matching thread. I insert a plastic ruler in the pocket so I don't accidently sew the pocket shut.