I think the food technique is the big one. Maybe I have a picky stomach, but it took me a long time to narrow down what I can eat and how much I can eat. I don't know what it is, but somewhere between 6-8 hours I just don't feel like eating any more and I have to force myself to do it. It's almost like I subconsciously lose my urge to eat because I know if I bonk I'll have a reason to quit riding. I'm a big fan of the Hammer Nutrition stuff and I'll usually mix up either 2-hour or 3-hour bottles and just remind myself that I need to have 1/2 or 1/3 of a bottle every hour. (Plain water is a separate issue and I tend to do OK on that by feel alone.) That, to me, is the most tedious thing about riding long distances and any change in that routine can turn into a big problem down the line.

As for technique, riding a bike is fairly simple from a purely physiological point of view. The big things that can ruin a ride tend to be mental in nature. Get too excited and go way too hard too early? That's a mental mistake with physiological symptoms. Same goes for mashing a huge gear on a climb, messing up nutritional strategy, not training enough, etc. It all comes down to experience in the end and most of us know what needs to be done. The big thing is having the discipline to do it.