I have read alot of the post concerning this question. They are for the most part good advice and have helpful tips in them. But remember that each club/ball combo reacts differently to any situation. Note that I said club not club set.
For this reason although I can use these diffent post as guides, I have taken the time to map my wedges and irons out. I freely admit that I have not spent equal time with all my clubs doing this, as I break my irons down into a few diffent categories: the zone clubs, the placement clubs, and the surgical instraments. Because of this I have spent varying amounts of time working on each group.
For the zone clubs (3wd - 5iron) I have done this only enough to see how spin and rough will effect the distance and any associated roll out. I use these clubs to get the ball to portion of the green or fairway. Due to the precision/forgiveness ratios multiplied by length of shot, any super precise result from these is a welcome bonus, however you wont get a chance at those results unless you really know what each of your clubs can and can't do.
For the placement clubs (6iron - 9iron) I use these clubs to try and nail an exact area on the green or fairway, by area I mean trying to get the ball into a box less than 2 yards square. I have spent much more time in practice mode repetitively hiting the same shot over and over with spin and power combos so that I have a very good idea of what each shot will do in a given situation. This is what I refer to as mapping the club, by using mulligans I have been able to hit exact same shot with the exact same conditions over and over.
For the surgical instraments (all wedges including the PW) I use these clubs to try and keep the putter in the bag. With care and practice these clubs are capable of sticking the ball within 1-2 feet of your target consistantly. But to do this you need lots of practice and experiance. I have spent approximately 3-4 times as much time mapping these clubs as i have on the 6-9irons.
A big note here, Every time you upgrade either clubs or balls the previous results become historic info. This info is useful in a guidance sence but it is not current, so you will need to re-map the clubs. The historic info will help here as you will reach the results much quicker because your theorys should be based more on facts and less on guesses.
If you have read this far are you getting the idea that it takes experiance (read practice) and lots of it to get a solid grip on handleing the challenges this game can and will throw at you?
If you say yes, then you are on the path to gain the knowlege in a systematic way that will help you.
If you say no, well then you are going to start looking for the magic formula and run around in circles cussing and moaning aobut how this game is screwing you.
The funny thing about circles is you end up right back at this point with a little more experiance, and get to make the choice all over again. You can get this experiace either way you chose but to improve you will have to acquire it one way or the other.