Gareth, wonderful posts.
There are really some very basic things that will set folks up for a much better Fundies (or any other GUE class) experience. I've learned a lot of these things the hard way.
1. Don't change gear right before a class. It doesn't matter how good you are, gear changes can throw you off, and being thrown off adds stress to a class in which you are likely to beating yourself up, anyway
These classes get scheduled way in advance, so you have plenty of time to acquire and use whatever equipment you are going to use during the class.
2. Wear appropriate exposure protection for the conditions, and be sure you are familiar with and comfortable in that exposure protection. Changing to a dry suit just before a class violates rules #1 and #2
The second half of this is, if you are diving dry, make sure your seals and zipper are in good condition, and consider bringing appropriate backup exposure protection in case you have a terminal drysuit malfunction. (Cave 2 would have been a lot more comfortable, had I heeded this one.)
3. Stability is the key to Fundies. Practice hovering while swapping regulators or removing and replacing a mask. There is no specific "technique" to these skills, so you aren't going to learn anything "wrong" by practicing them -- but it will give you a good idea of how stable you can remain while task loaded. If you are doing this kind of thing in a pool or without a buddy, make sure you note not only any depth variations, but also whether you are moving in space. Working as a team requires that you be able to do these things and remain STILL, or your positioning will suffer.
4. Class is kind of inherently stressful, largely because we are who we are. But being well-rested and well-fed helps a lot. One of the things the students in FL apparently weren't prepared for was not taking breaks for food. (We had a whole THREAD on appropriate Fundies snacks before my class, but I guess that information is no longer circulating as it was then.) Make yourself eat when you can, even if you aren't hungry. (Again, I would have had a better time in C2 if I'd done this.)
5. Develop a team spirit. It helps if you all stay in the same place. This is team diving -- we help each other and work together. Where you have students of different abilities, or if people are doing poorly, it's easy to get angry with one another, and that's not what we are supposed to be learning.
And a couple more that are my personal decisions, and may be arguable: If at all possible, do the class in conditions with which you are familiar. If you don't dive in current and try to do a class there, you've added unnecessary stress. If you don't dive in cold water or low viz, again, you're going to be stressed. I've seen a pair of students bail out of a class because they couldn't handle the bad visibility where they had traveled to take it (and those students subsequently finished the class at home without problems). If you can take a class at home, do it -- you have access to SO many more resources there, than you do if you have flown 1000 miles.
Pick your instructor. Although everybody who teaches for GUE has passed standards for a high degree of skill in diving, they are not all equally good teachers, and they all have different personalities. Being in a class with someone whose approach just doesn't work for you is not a recipe for a good learning experience. (This is another place in which traveling a long way for a class can work against you -- but if you are going to do it, really try to talk to some other students of that instructor to find out what his style is.)