Changing my whole swing, where to start?

Pretty new to golf and have been improving. Had a rough start, using the wrong clubs for years and playing baseball my entire life has giving me a lot of habits and things I need to break. Still not good by real standards at all. I was a self taught golfer up until Friday, but had found a swing that was working. In my last 9, the first 5 holes I'm on the greens and at +1. Next 4 holes I'm in shooting 7's and 8's. I got my first lesson from someone really good. His last round was a 64 on a 71. So, since I am a 20 or so handicap on average, I gave it a go. I get a 2 hour lesson for free (I use to teach his son) where my whole swing seems to be wrong, and I knew it was the whole time. Then he gave me about 20 things to think about from my grip to firing through. I've been working on this swing everyday since Friday and am getting it a bit better. Hitting the range after going from standard to oversized grips and changing my whole swing was very humbling. I have been doing the wiffle ball thing in my back yard just trying to get the motions down but 20 new things is like a huge mess in my head. So much thinking going on during the swing.

Any advice on this? What to work on first?

The grip is easy

Back swing is kinda tough with trying not to turn my hips. (Baseball stuff) As well as not trying to buckle my front knee while going back. (baseball as well)

Follow through is so easy, but tough as I often forget to do it right because I'm so worried about having the correct release and arms in the right position on the back swing

Releasing at the right time and using that to get power has been completely new for me.

Keeping my hands in.

inside of my arms facing up..

etc etc..

where to start?  I'm going from hitting the ball pretty straight, just topping it a few times per 9 and having a slice on my driver and lower irons, to having a lot more shanks directly off to the right. Bad shanks. What's the main cause of this? Not releasing at the right time? Not rolling my hands through correctly? I just got oversized grips and the guy said it would be harder to roll through, but I am 99% sure it's my swing and not the grips although he said I was border line midsized. Wrist to finger is 8 1/2 and middle finger is 4.

any help would be appreciated.

thanks!

Glad to see your enthusiasm!  If I may make one suggestion, since you seem to be a baseball player type I would try to think about the golf swing being more like pitching or throwing a baseball rather than swinging a bat.

It is no coincidence that pitchers who throw 95+ mph have a sweet and slow windup like a takeaway, and use their body to hurl the ball using their arm as leverage.  It is similar to golf in that you use your body to hurl the clubhead using clubhead lag as leverage to multiply power.

Best of luck and swing easy!

You can learn all of the positions and movements that are necessary for a good swing, but how do you make it all happen perfectly in the one second or so that you have from takeaway to impact?  That's why I use the lead shoulder key as explained in the golf swing master key instruction .

lot of good details but try one thing.

if your instructor told you i'll give you $1 for every shot that you had good tempo...and you wouldn't have to worry about where the ball went...would you?

of course you would. work on 1 thing. your tempo. forget about your grip, your stance and where the ball goes...if it slices 50 yards who cares. it doesn't matter. none of those count.

go to the range and practice on your tempo. smooth 1-2 swing.

once you get the true feeling of how you swing from start to finish...then work on the technical aspect of your swing.

Grip, just because how the club feels will dictate alot of how you take the club back.

Go in the order that the swing goes.

1) Grip

2) Address

3) Backswing

4) Downswing

5) Followthrough

This is a bit abbreviated and their are certainly very important points in between but its kind of like baking a cake, you can put nice frosting on a crappy cake to make it look good but if the underlying cake is crap the whole cake is gonna be crap.

It is true that a golf swing is more similar to pitching then hitting. In hitting you use fast small muscles to generate a lot of speed in a short time.

In pitching and golf you use big slow muscles combined with a lever (your arm and/or club) to create high speed over a longer period.

First, work on finding an instructor who will give you one or two things to work on, not twenty. Good grief!

1. Start with your setup - grip, stance, posture, aim, ball position.

2. Then learn what you're supposed to do at impact. The easiest way to learn this is via a pitching stroke, not a full swing.

Get lessons for both of those things.

3. Oh, yes. Have an instructor show you how to putt. Doing it right is not as easy as it looks.

First off, thanks to everyone who replied! Taking everything in with a deep breath.

funny you mention easiest way to learn is pitching. Went and got my second lesson from this guy today and I was saying "lets head to the range and fix up this swing." He took me to the pitching area and we worked on that for a good hour first.   Went to the range from there and my tempo is off. Way to hesitant on my back swing. Always thinking about if every detail is right.  Once I got past that I was hitting the ball straighter and further than I've ever hit it. Not consistently, and not always straight forwards, but straight. Most of the missed hits when straight but off left. I feel like I'm learning to hit the ball all over again, but this time, I've got a chance to get a good swing down. Wish it wasn't raining all weekend.

Guy said my main problem was I was hitting with my left hand, not releasing or firing through, or kind of stiff arming it for power. Now I'm releasing, firing through, rolling the wrist, keeping my hands down, and all of that, but the release timing is off. I think I release to soon, or sometimes release and don't roll over so it shanks way right. But yeah, the most frustrating part is the "non-smoothness" of the swing. Feels clunky and jerky because everything is making sure my knees and arms are in the right spot and right position. A few times I just used my old back swing and released and fired through while rolling the wrists and launched the ball out there nice and straight. My worry is I'm going to practice the wrong way and have to relearn the mechanics.  I'm hoping it will just take longer, but all come together at the same time for a smooth mechanically sound swing. At least that's what I'm hoping, but for now, it feels like riding a bike with square tires. Seeing where you want to go and slowly getting there, but the ride there isn't a very fun.