Just feel like your left elbow is over your left toes at the top of your backswing and swing it down the line thru impact. Straight back and straight thru, with your left elbow that is hehehe.
Moving on...
Turn like you in a barrel or a phone booth
Just a rotary motion around the angled spine, you'd think it would be easy.

Like many amateurs we can get in a pretty good position at the top of the swing, but then...

spine angle is lost. Let's look at Els below...

and spine angle after impact

its the same angle. I have looked at vids of my good player friends and us not as good players and this is the defining view.
My swing thought now that is working somewhat is 'replace where the left ribs are at the top of the swing with the right ribs at impact'.
Pull your left elbow past your face as pictured below...
The faster you pull your left elbow past your face, the easier it is to keep your spine angle. That is why you need good core strength. But better yet, build up those forearm muscles with curls or whatever as much as possible.
Then keep your left elbow pocket looking at where the ball was as long as possible as pictured below...
Only two thoughts=left elbow pocket over right foot at top of backswing and left elbow pocket looks at ball thru impact.
Putting and Chipping-
Thru impact, pull your left elbow past the ball while keeping the elbow pocket looking at the ball and then keep the left elbow pocket looking at where the ball was for as long as possible after impact.
Yep, one size fits all.
Use gravity to fix your golf swing. I'm not copying anybody on this, these alone are my ideas, and I like them. You need to maximize gravitys effect not hinder it.
Gravity pulls the most on your swing when the left arm is angled just below the horizon.
Then gravity pulls on the club to a lesser extent when it is just angled slightly below the horizon. Slightly below the horizon is where gravity peaks on a spinning object.
Gravity emanating from just below the horizon, pulls on your arm and swing, like a magnet, as long as you keep that left arm tilted below the horizon as long as possible in the downswing. You can't swing down any faster than gravity will pull your arm down, but you can hinder gravitys help if you lose the below horizon left arm angle too soon. Now, done correctly, your weight will have shifted without you ever thinking about it. Once you are in the slot you are ready to add to it with all you've got.
Start very slow keeping the left arm tilted until you can build up a rhythm and speed or just do like above and keep the left elbow pocket pointed at where the ball was as long as possible after impact. Its not very long, its a feeling not a mechanical motion per se.
Sure there are other forces working in your swing but thinking about
only what the left elbow is doing, which is pointing at the ball, the hands for instance take care of themselves without flipping thru impact.
Repeating...
PUTTING & CHIPPING
Keep the 1. distance from your right elbow to the putterface the same thru out your putting stroke while rocking your shoulders and 2. pull the ball to the cup with your left elbow pocket looking at the ball and where the ball was after impact. You will hit it so solid.
1.

2.

RESET your golf swing.
To get back to square one where you need to hit the ball solid and straighter, just feel like you are returning your right shoulder at impact to where it was at address.
The right shoulder tip position is about the only constant between address and impact positions.
uh-oh below
2010 Collapse at Pebble Beach(above.) Right shoulder tip is jutted out to soon just before impact. It should be in that position well after impact like the pics below.
Right shoulder tip will be slightly lower, it just can't be jutted out toward the ball target line. Shoulders may be more open, but that is from left shoulder opening, not right shoulder jutting too soon.
A little squat in your backswing where you "sit into your right hip" can help you from coming over the top.
I've got to control my LEFT ELBOW.
Never let it get outside toward the ball in the downswing from where it was in the backswing. I like to feel like my left elbow is swinging down under my sternum. Pic blue line below right shows left elbow inside where it was in the backswing.
TO HIT IT LONG pull your left elbow as fast as you can past your face just before impact as you enter the slot. This is when you want to floor the gas pedal. Then when the left elbow starts to move to the upside of the letter 'U' keep the left elbow pocket facing where the ball was at address. The left elbow will now quit moving laterally and this is what snaps the clubhead thru impact. Remember, keep you left elbow under your chest, don't let it fly out toward the ball/target line, keep it under your chin.
Also, keep your elbows comfortably toward each other, don't let them fly apart.
SECTION 4b.
This section should be used for video analysis and practise only, not for swing thoughts on the course.
Backswing=Left elbow stays in line with left shoulder tip until arm
is parallel with ground. Right wrist snuff box stays facing up not back so right forearm doesn't rotate to soon. Clubshaft lines up with right forearm because arms are swinging in sync with body.
Downswing=Left elbow stays just inside or even with where left elbow was in backswing. DO THIS BY KEEPING YOUR BACK TURNED TOWARD THE TARGET AS LONG AS POSSIBLE and

feel like your left elbow is swinging down under your sternum.
What's interesting is the left shoulder holds its vertical position while the right shoulder lowers straight down to be nearly level with it.
Even after impact the left elbow(below) is under the left shoulder tip. They have moved thru impact with the left elbow staying under the left shoulder tip.
PLANE-The only plane to concern about is shown below
You must have some Ulnar Deviation(slight bending down of the thumbs) thru impact or else the clubface will be open and you'll block it to the right of target. Commonly referred to as a 'hand block'.
The clubshaft being in line with the right forearm is paramount along with a flat left wrist thru impact.
DOWNSWING=I've had fleeting success using a squat in the backswing that loads the glute muscles, but when it worked I was hitting the ball further than ever. But I've lost it, sure was fun while it lasted. I keep searching to get that powerful swing back. It felt like I was pushing down into the ground with my right foot in a slow deliberate way right thru impact.
Makes me wonder about what I read below..
http://www.powergolftraining.net/to-improve-your-golf-swing-power-be-a-tree.html
In describing the swing of J.B. Holmes, noted golf instructor David Leadbetter has this to say…” Starting down, his legs get into a squat position, which lets him use the ground as resistance and create an unbelievable energy flow from his legs, up through his shoulders and down into his arms and the club.”
Using the ground as resistance and the creation of energy flow from the legs are two important components we focused on for generating power in our techniques at the kung fu school.
Read this online post...food for thought...
*The reason pro golfers are able to smash the ball is that they swing loosely, not tensely. Every muscle in their arms and body is at ease until the very last instant (more or less) right as the clubface is about to make impact with the ball. THEN they tense up their muscles and "snap" the clubface through the ball.
Speed chain training seems to make a lot of sense.
The chain links are smaller and lighter toward the grip and progressively get larger so as your swing enters the impact zone there is more force being applied. Would the swing fan do the same thing?
BASIC GOLFER DOWNSWING
If your just starting golf or if your in a slump, make sure you get used to this first.
The simplest and most important thing that must be done in the golf downswing is to keep the clubhead lagging behind the straightish left arm until impact. Not hard to do if you concentrate on this and get your timing.
You can have a decent swing just by doing the above.
*THIS IS THE WILKYWAY*