I'm afraid I can only show you a little way further (or possibly down a blind alley :-) ). I've discovered a couple of things so far.
First, if you can get geotrichum candidum going at the start, *and* you can keep the rind smooth, then the cheese will be magically free of anything except geo for the first month or so. Blue especially loves cracks and crevices. It also likes sharp edges like the little stipple patterns from cloth marks or holes in the mould. I've been practicing pressing with the cloth on and then doing alight press at the end to erase any marks. It's fairly easy for high moisture cheeses, but much more difficult for hard cheeses, I've found.
To get the geo going, it's important that you don't over salt the rind. Geo doesn't like salt concentrations higher than 3%. After you are finished salting/brining the cheese, if you need to wash it, use a 3% brine solution. More than that actually encourages blue because blue can withstand up to 8% salt. Both the blue and the geo compete for the same food, so your goal is to allow the geo to win.
Geo is actually a mould-like yeast. It needs oxygen to grow properly. It's important to open the boxes and flip the cheeses every day. It also likes a higher temperature 16 C is fine for it, whereas blue likes colder temps. It's common to have a higher temperature period before putting it in the cave -- some dairies have a "yeast room" for this purpose. I have found, though, that you need humidity. Because of that, I've found that drying out the rind (as is often suggested) seems counter-productive for geo. Instead just wipe off any standing liquid and put the cheese directly in the box. If you get black spots on your cheese that stain the rind (mildew), I have found that this is due to not enough gas exchange. Make sure to air out your boxes every day (I open then, take out the cheese, and turn the box upside down to pour out the CO2 -- it's heavier than oxygen). Gavin Webber's vent idea will not work at all because the CO2 just sits in the bottom of the box (one of the reasons he has so many problems with natural rinds, I think. Of course he looks after his bloomy rinds perfectly which is why they are so nice :-) ).
Geo actually sends shoots down into the rind. Once you get a good bloom of white, it seems to be beneficial to wash the whole cheese and let it regrow. I found this advice somewhere (maybe buried in Caldwell's book?) Apparently this was the secret of some famous affineur. Every time I've done it, the geo grows back more vigorously and well spread than before. So before the food runs out, I *would* do that as long as you have decent geo coverage already (day 11 or 12 is a fine time to do it, I think -- I try to get it done by day 7, as long as I have white blooming).
Once the blue gets on the cheese late stage, I have not found a way to combat it. I have a Caerphilly in the cave that is at least 50% covered now, having spent the first 6 weeks or so snow white. I've been trying to get my cheeses to get a good succession into the next stage of moulds. Unfortunately with this cheese, I let it get a bit too humid and now it's got b.linens going along with the blue :-) I'm going to let it go until it doesn't look scare any more :-) Theoretically, when the rind dries out, all mould will die and turn brown. You get this kind of crunchy crust on the outside. I'm going to let it go to see if it gets to that stage.
However, I have not gotten *any* cheese to go to a succession without blue yet. I'm sure it's just some subtle thing I'm missing. Or it may be that my cave lacks the appropriate moulds. I'm also thinking that I just need 4 or 5 sacrifice cheeses to build up the succession moulds in the cave.
BTW, there is one other thing that I've started doing with surprising success. I no longer sterilise my maturation boxes or bamboo mats. In fact, I had one bamboo mat that was covered in blue and I thought, "If this cheeses is going to beat the blue, then it needs to do so because the environment is right -- not because there is no blue." I have no way to *really* get rid of the blue. So I did my geo favouring thing and all the blue disappeared from the mats. So now, I'm treating my mats as special magic that holds the moulds that I want to keep. By keeping them in the right environment, they will help the next cheeses seed the fungus I want. It was a leap of faith, but it seems to have paid off.
Now if only I can go longer than 2 months without the blue :-) Keep going and make sure to report your successes and failures so we can all learn!