ADYTHEGOLFPRO:
Would anyone please be prepared to teach me how to putt better?
Look at the FAQ puttng tips if you haven't already, there are some good guides there.
As for change on green, I too did well at Very Fast, then struggled on Tournament greens. It just takes some getting used to.
There are essentially 2 factors regarding putting - the break (left right) and the distance.
Distance is easy. The number of time I have 3 putted using the below formula I could count on one hand. I guarentee you will be very close using it.
Whip out your computer calculator.
Take the number of feet - for every inch up add 1ft, for every inch down minus 1ft from it. Then divide by 1.4. So for example lets say you are 17ft away and it's 2 inches up hill. 17+2 = 19/1.4 = 13.57. As it's uphill sightly, then you should look to hit at 14ft. It depends on the green but you might want to hit it 15ft just to make sure it gets there.
If it was 21ft away and 2in downhill the formula above would give yoy the same answer 13.57 - but as it's downhill use it more as a maximum speed to hit. 13ft would probably get there - maybe hit 14ft (at very most) just to make sure.
If it's a lot down hill (more than 6 inches), or a lot up hill the you might want to take off or add a few yards or divide by a bit more (1.5 if down) or a bit less (1.3 if up). Some greens are also just faster than others.
The break is a bit harder. There are a few formulas, but from what I understand most of the top putters do it by experience. If you have played 5 putts that are similar you will have a good idea of how to sink a putt like that. If you could play the exact same putt 5 times in a row, even if you were 100ft+ you would probably get it very close after yr 5th attempt. When you have played a lot of putts some will be similar to others and you will do better.
A general putting tip I only just started using but found helpful was switching to "chip". Using that you can move the grid. Try and get it so the line to the hole is within 1 straight line of grid squares. You can then see a much more accurate idea of the break to the hole. Click and hold and watch the speed of the dots. Release and cick again and the dots will start again in the middle of the grid square.
I generally look at the putt from behind the hole. Sometimes it looks different from the front view but find looking behind the hole to be more accurate.