The descriptions floating "The Internet" are AFAIK accurate except that the fabled zipline (and some comments about make sure you have pulleys etc etc) are historical and the first bit of tomfoolery is walking a pair of tensioned steel wire ropes (hand/feet)
The first big chamber (between first and second abs) is definitely an area to minimise your time and be gentle and quiet
I believe user SamMill kindly placed some bolts on the only (expected) "up" in case of rope vandalism to make it possible to escape, don't think there's been any more problems, did hear of someone doing the CRTT about 8 weeks ago and they had no probs
Route finding in Croesor is "follow your nose" there is only one route choice moment and I believe it's customary to leave first timers in the dark on that
After the chamber of horrors it requires some navigation to get from there to 9 Adit, in daylight the instructions are obvious, my first time was in small hours of morning and made one section harder to navigate if unfamiliar.
Adit 9 used to be very nearly wellie depth in places probably most descriptions have that, but now that is much shallower. Personally I recommend parking at Tanygrisau SH 455 683 and not the Croesor car park (but it's up to you) navigation from the "exit" to the "entrance" that way round might need careful navigation especially if misty and better at start than end IMHO and then you have easy walk back to car at end. Don't try to walk-in wearing trainers while carrying your wellies, or you'll get soaked feet before you even started - probably as a caver you wouldn't do that anyway
Note: Tanygrisiau lakeside cafe SH 449 682
ENJOY!! it's a brilliant playground