No Snacks, no sweets, no seconds. Except on Days that start with S. Too simple for you? Simple is why it works. Look here for questions, introductions, support, success stories.
There is no actual ruling on alcohol. Reinhard himself is rather fond of an occasional and limited quantity of beer and has a system called 'glass ceiling' whereby you put a 2 drink limit on it per day. I personally think 2 glasses of wine is OK. 3 or 4 glasses is probably pushing it though, but either way it's not actually covered by NoS, so you haven't 'blown it'.