Just last week I was able to make it to a single digit (just barely), descending from a 20 to a 16 to a 13, and now 9.9. Here's what I now know:
* I'm not sure my drives are better, but I've eliminated (usually) the OB's, hitting into hazard, etc. Some days I'm often in the fairway, but other days I'm in the rough. Essentially I've gotten my drives "good enough" for a single digit.
* I've worked had to round out my game: distance wedges, sand, chipping, punch shots, etc. Again, I don't think I'm great in any one of these areas, but pretty much good enough.
* One thing that has made the difference is mastering the six foot putt (or at least making most of them). You've got to be able to get down in two putts on nearly all of the greens. For me that was making sure I made nearly all the six footers and less, and getting up and down with less than perfect chips. I still bogey more often than not when in a greenside bunker, but at least I'm eliminating doubles.
* Perhaps most important is that even though my irons have gotten better, I've gotten much more conservative when aiming at the greens. I almost always go for the middle of the green on shots greater than 100 yards. For distance wedges from 100 to 50 yards I might favor one side a little more. However, I never shoot directly at a pin unless that pin is also in the middle of my "safe area" in the green. Get it on the green, two putt, next hole. If I birdie, probably because I hit a good putt, not an aggressive approach shot.
* Finally, I've become a believer in "boring golf." The first hole at my course is a Par 5. I could hit a driver, and maybe hit a FW wood that might be on the green that might allow an eagle putt, that ....you get the idea. Instead, I hit a three iron the the safe area before the bunker, then a 4 iron then a short iron to the middle, then two putt. Keep it boring.
Obviously I have a lot of room for improvement, but at least can now claim single-digit status.
Good luck.