The basic darning kit:
First, Don't let your holes get this big, as I did.
Circle hole with running stitches and place parallel stitches across hole. Stay loose; no knots, and don't attempt to close the hole up by bunching it together. This will only create bulk and thus Blisters!
Weave back through perpendicularly, alternating over and under, just like when you made those cheezy potholders in summer camp.
(In this case I was going for the red/grey sock monkey look.)