OK, here's my real hint. Use clear thread to sew on the patches. Then you don't have to match the color of the patch and if you sew really crocked no one can tell.
From the front: perfection
From the back, you can see what a bad job I did, but thanks to the miracle of clear thread it will be out little secret.
(the dark spots are from left-over adhesives)
I know that some people use no-sew adhesives for patches. These are great if you never need to remove the patches, but as often as we move, they don't work for us.