The only good advice about attempting Crib Goch, is to climb it in favourable conditions.
If its raining, then the scrambling on wet shinny rock up the Eastern flanks of the mountain will be far more difficult than it should be.
The biggest issue would be wind, and even though ive seen some walkers traversing its crest in far from ideal conditions, its advisable to attempt it only when the weather will allow.
Its unfortunate that the majority of walkers have not got the luxury of the perfect weather for a traverse of Crib Goch, but the ideal weather is dry and calm.
Mist is not so much an issue, as ive crossed it in very poor visibility, but that was in dry conditions with little or no wind.
Just treat the mountain with the respect it deserves, and even though it has a fearsome reputation, its not a difficult mountain to conquer, as long as a bit of common sense is shown, and one realises how acute the exposure can be for some walkers.
Once your actually on the ridge, there is nowhere to hide or escape, and turning back and returning the way you came is actually more difficult than soldiering on and finishing the ridge.