Many people find lacing the back of needlework essential to keep the stitching taut when framed. But finding good information on how to do it has always been a struggle for me.
This outstanding lavishly illustrated lacing tutorial from Plays with Needles shows you how to lace step-by-step. Although she is lacing fabric, the process is the same for needlepoint.
Thanks to Denise at Craft Gossip for pointing this out.