Maintain solid spinal alignment. Most people who are new to this will want to cheat the single-arm plank by creating cervical hyper-extension and tilting their heads up. This strains the neck and places excessive tension on the lumbar spine by causing the hips to sag.
Focus on keeping a tall and elongated neck throughout rather than tilting the head up or down.
This isn't my usual type of article. Rather than launch into a specific training program, TC's given me this opportunity to launch into an Alwyn Cosgrove rant. A brief warning for the timid, however: I am the king of the politically incorrect.
Over the past year or so, I've been swamped with requests from readers who want a program that focuses solely on maximal-strength development. What I'm referring to is a maximal-strength focused program that doesn't induce bodyweight from hypetrophy.