Correcting Fishtailing In Freestyle

How do you correct "crossing over" or "snaking" in a freestyle stroke? Are there drills? I can't shake it. I finally filmed my stroke and was told before to do so to see that my entry arm (on a right stroke) is entering the water across near my left ear. From my vantage point, I see the right hand when I'm swimming at 1 oclock or slightly to the right of my right shoulder. I look at the film and sure enough, my right hand is coming across, near the left ear. In the water, I'm feeling the hand is entering the water and catch at 1 oclock. My gliding arm, the left, I see is not straight, but angles a bit back to my right side. It looks like m right arm is coming over my left hand. And I'm really over rotating on my left shoulder. Right elbow is way up, almost immediately vertical to my right ear. Alot of this is effected by total immerssion book I read, to swim on your side. Not sure how to fix this, or what the culprit is.