ANZAC was a good amateur drain, its still OK. There's a knee deep damn extending all the way from the entrance to the Chamber so be prepared to get wet. Walk along the side, not down the middle.
Check the weather (obviously). When it rains, no drains.
Don't take spray paint or anything of that nature.
Take a spare torch.
Mmm that's about all I can think of. When I explore I always take 2 torches and my phone. That's usually all I need. If I could be bothered carrying a backpack I'd take some water too but usually I can't be bothered.
Wander often. Wonder always.