I've been playing amnesia for a while now and I think I understand the monster behaviours fairly well now.
The most important thing you need to know is (as a rule of thumb) to hide. :D
Avoiding detection consists of 3 parts: 1. Reduce your sound (crouching helps) 2. Reduce visibility 3. Increase your distance
If the enemy sees you going in a room or corner, it is only bound to follow you to some extent. If there is nowhere in the room to hide, (such as no closets) they won't come in the room and will just stand at the entrance for a while. (at least that's what happened to me.)Also, they will not travel long distances to chase you. After you either run a certain distance away or hide for long enough, they will de-spawn so, not to worry.
So therefore, if you pretty much break visibility between you and the monster and are able to stay for about 10 seconds, then you're safe.
The developers made the monster fairly easy to evade as to not excessively frighten the gamers and avoid more "effect" than necessary. :P
All of the stated above were based on my own experience and gameplay. So, don't underestimate them; you should still be extremely cautious.