No two locks are ever the same. Each exhibits their own 'personality', with little quirks and characteristics that will leave you either loving or loathing them!
Whether small narrow single locks or broad, long automated commercial locks, there are a few things to always bear in mind:
This is all pretty much common-sense, however the most dangerous part of any lock is the CILL - a concrete or stone ledge lurking under the water. The position will usually be marked in white paint on the side of the lock. Keep the boat well clear of the CILL, as the water goes down the boat can easily catch and this is a common cause of sinking boats in locks, so:
Having said all this, locks are some of the best, and most fun part of boating. Many of the older locks still bear the Masons mark, carved into each individual stone or block. This is how the 'Gaffer' would calculate daily pay, based upon the number of marks and consequently, work undertaken.