When you are getting into your stance imagine that you are a middle linebacker.  Keep on the balls of your feet with your knees slightly bent.  Then imagine someone standing in front of you that is trying to push you in the chest to knock you over.  If you are balanced they would have a hard time moving you off your stance.  If you are leaning too far back it would be easy to knock you over.  If you are too far forward you will feel as if you are falling into them.  try to ask yourself at address, what would happen if someone pushed me in the chest.  Hope this helps.   It did for me.

Exactly what Brian said.

Knees slightly bent.  Weight on balls of feet.  Your nose should line up with your hands at address.

Try keeping your hips stationary as long as possible.  Should still be parallel to target  when the club is waist high.  Lower body should be quiet going back and dominate on the downswing (hips start the downswing).

The "big 90 degree backswing" is BUNK!  If you notice the pros are going to a more compact backswing and keeping the front foot planted.

Stay behind the ball until through impact.

Also what causes swaying is too wide of a stance.

I concentrated much more on what you said last night. Before I got into the 'middle linebacker' stance, I stood straight up and extended my arms out and then bent straight down into the stance. This insured that I was standing the perfect distance away from the ball. It helped so much. While I was hitting my 5 iron great a few days ago, last evening I hit my 4 iron even better. I bought my irons in January, and needless to say, my 4 iron is the shiniest club in the bag. I never even bothered to hit it. Standing 180 out on my third shot on a 600yd par 5, I put the ball on the center of the green. Had a great time last night. Thanks for the tips.

I feel your pain because my game went down the toilet between July and November last year.  I had a tendency to hit low pulls with my fairway wood and hybrid and would often yank my irons and wedges 5 yards left.  Driving was actually quite good.  I was shooting scores of 47 or 48 for 9 at Adm Baker South or Riverwalk and was shooting close to bogey golf at Oaks North; considering that my normal score at the two regulation courses was about 43 and about 2-3 strokes over par at Oaks.  I also had some issues with casting and would bury the club at impact sometimes.

I also had an issue with shankitis in 2008 that started when I went to a more upright swing (worked great for the driver and longer clubs but it would pop up on the short clubs without warning).   One thing I had to do was bend my irons more upright. 

Since December I have been playing the best golf of my life (shot 39 at Adm Baker and 40 at Riverwalk; Shot lowest score at National City - +1 and even played subpar for 7/9 holes on the East course at Oaks).

In regards to the "linebacker" stance.....  I was given the tip about an athletically ready stance by one of the teaching pros at www.allexperts.com (John Brott).  The wrestling stance is similar but you have one foot back and one forward (mainly so you can sprawl if your opponent tries to shoot in for a takedown); I was on the wrestling team in HS.

I would say that 99 percent of all golf swing faults are due to loss of balance and standing too close to the ball.  Also another pro gave me an interesting tip about finish....   If your front foot is flat it causes a push slice - weight should be forward part and heel.

Try thinking about covering the ball when you swing. Like a spotlight in the middle of your chest. Focusing on this may keep you from swaying and help with balance. Also, it's never a bad idea to club up and shorten that swing until you find your tempo.    

Recently, I read some comments by Brad Bryant (Dr. Dirt) now playing the Champions Tour. Perhaps these comments will help you all:

"So…learn to hit a golf ball without moving your knees. In fact, don't move your knees at all. Hey, if you can only hit the ball fifty yards, without moving your knees, that's great. And as you increase your distance, then begin to move your knees slightly.

Always remember that your knees only move as much as your shoulders move. They can never move farther. Most people move their knees considerably farther than they move their shoulders. They'll move their right knee to the right on their backswing, their left knee will come in, and both knees will get out from under the shoulders-and they lose the support in their golf swing.

The thing that has helped my game, and I'm probably one of the most improved swingers on the Tour right now, is that I learned to keep my knees underneath my shoulders throughout my swing. My shoulders and my upper body are always supported by my legs, and my balance remains good. As soon as you get off balance, you can't hit good golf shots.

Strangely enough, on one teaches much about balance.

The way to achieve balance is to stand with your spine fairly erect and straight-not curved-and then you get your knees under your shoulders. Don't get too bent over. If you get so bent over that your shoulders are closer to the ball than your knees, you'll be out of balance. The way your body is make, to hit a golf ball you need to stand where your knees are almost directly under your shoulders in a vertical position with your spine fully erect and straight. If you'll do that, you'll have good balance."