Over the years I've changed what feels like hundreds of things in my swing in order to home in on something approximating consistency and I'm still working on it. Below are the main points I have distilled my swing into and I'd be interested to hear how they compare to other forums users (I am right-handed):
I try to keep my grip as loose as possible, Varden style. My right thumb points straight down the shaft.
I favour a narrower stance, generally with my feet no wider the shoulder width apart for irons and perhaps fractionally wider for the driver. My experiments with wider stances did not go well and left me feeling very restricted during the swing. My right foot I try to keep square, the left foot is flexed out slightly.
Irons are generally out of the middle of my stance, driver I set up in line with the left in-step as per the classic advice.
I try to keep my backside out but I don't worry too much about keeping my spine straight since it frankly hurts to do it over a long period of time. I suspect that posture is something that starts to go as I get near the end of a round and tiredness sets in.
Backswing - Wrists
I like to cock the wrists early and ensure the clubhead always stays in front of the hands on the takeway.
Backswing - Arms
I keep my right elbow tucked in as long as possible on the backswing. I'm unsure exactly why but this tends to produce straighter shots. I suspect this may be creating a more optimal swing plane but I would be interested to hear others' thoughts.
Backswing - Hips
I rotate my hips a fair amount on my backswing since I find a lack of rotation often results in a sliced shot, although I do worry sometimes that I am overdoing it somewhat. My belt buckle may have rotate over 45 degrees by the top of the backswing.
Downswing - Start
This is quite key for me since it seems to be the area that causes the biggest problems if I get wrong. Generally I like to start my downswing with a slight outward turn of the left foot which causes my hip to bump/slide slightly to the left before the arms start their downward journey.
Downswing - Hips
Contrary to some advice I have been given over the years, I do not attempt to rotate my hips any more than they naturally do as a consequence of my arms swinging through.
Downswing - Arms
I normally try to get the right elbow back in as fast as possible and get my hands "deep" into the lowest part of my swing.
Downswing - Wrists
I try to keep my wrists cocked as long as I can but I honestly could not tell you at what point they hinge.
Ideally I will be on balance with my belt buckle facing the target, weight fully on my left foot but sometimes I will find myself having to take a step forward. When that happens it's normally because I have tried to hit the ball too hard or because my stance was fractionally too narrow.