I edited the following to speak to everyone but it's basically what i told Seacliff.
Where I surf {guess where?

} I get to see a LOT of novice to intermediate surfers. The thing I’ve observed as most common when people are going backside is; people not squaring their shoulders/upper body to the wave. What that means is rotating the upper body. What IS happening is their bodies face the beach on bottom turns, their heads may be turned a bit to look way down the line some, but are not looking at the pocket or lip that is nearby so they run along the bottom of the wave often missing power/speed/positioning they could be accessing. Also from observation I have a strong feeling that most are unable to do a squat and have their backs of their thighs hit the calves while feet stay flat on the floor. A lot of people’s knees never bend more than 90 degrees if that, and of course most of the bending is happening at the waist. That is super common and it's pretty bad for control of the surfboard. If one is running and doing strength stuff it’s awesome, but it also tightens up the very muscles that are crucial to control and style. Surfing is interesting in that good style/form {esthetically pleasing to look at} usually equates to function/effectiveness. Bending at the waist is not bad if it’s proportional to the whole body, but basically all the lower body muscles/tendons {legs and ankles} should be pretty stretched out so a high level of flex is possible.
1. stretch religiously, get your self to the point of serious flexibility. have more than you think you need. you don't have to do a whole yoga routine, but a series of stretches every day, we're talking about 10 -15 minutes, will get things where they need to be. Hey, yoga will do the trick if you want to go that way, it’s awesome. Anyway, focus on legs and back. Hamstrings, calves and achilles are the main culprits in what I call
locked leg syndrome, where a person bends their knees a small amount and they pretty much lock there, then it's all upper body folding. Really hard to watch…..
2. air surf. practice moving in and out of the positions you see pros in, like pig dog stance and layback. if you can't do it on land, it ain't happening in the water. do that stuff on an indo board for even better workout/training. If you can get into that DEEP squat I'm talking about AND rotate your shoulders 90 degrees you're getting there. DEEP knee bends with the upper body remaining as upright as possible also a good/necessary thing. I air surf quite a bit, sometimes before a surf, it really helps get stuff in the muscular memory bank so it just happens. Everything is a work in progress for me, I still struggle some with that shoulder rotation thing and other issues, but it's gotten a lot better since I started practicing form on land and when I ride my skateboard. Oh yeah check yourself out in a mirror in your backside tubestance and see if it looks like more like Parko or Barney.....
Rotate upper body. {look where you want to go}
Get your freaking knees to bend. {WAY MORE}