Cider making is easy to get right, but when it goes wrong it is a miserable experience. If it does go wrong it is usually because of poor hygene. Some nasty bugs get into the juice and mess it all up. Therefore at all stages, be mindful of keeping clean. We are all covered in yeast spores (really, you breathe in millions of spores every hour) and it only takes one vigourous one to ruin a batch. So, clean and sterilize should be your mantra
A demijohn is a strange shape and there are few brushes that can get everywhere. However a short length of chain can act like a brush.
Siphon tubes are a pain and so after washing with soapy water I always sterilise mine.
Washing your hands
Don’t stop at the palms. You will probably roll your sleves up while working, so wash thoroughly up to the elbows to remove yeast spores before you start brewing.