There are probably more than I'm going to mention so I do hope that everyone will add their own:

Some of these will probably read more as Murphy's Law but basically I'm looking for those things in W&W which seem very true in life.

When you're in a hurry, some toad will block your way.
When you're in a hurry, you'll have to deal with Sebastio.
Those in life who have the least amount to say take the longest to do so.
Sometimes to get where you want to go, you need to go the opposite way (Serpent Temple elevator maze).
You can just be minding your own business, doing harm to none and someone will come along and flame you. (Earthsmedor)
You can try to help someone out but unless they want to help themselves, they'll stay the same (Torin.

They will hunt you down! (not sure that is a life's metaphor but I really like the saying!) :D

You often learn the most from the least likely people (Oakenmir & his 11 million XP)

He was not the one to spot the lever = He is not too bright.

Don't do a vegetarian diet!... Salads are dangerous!...

If you're by yourself and you go crazy, no one can tell the difference, including you...

Pick ups often include dancing. (groan)

When you're searching for something, it's always in the last place you look. (duh)

Ve haf vays of making you talk.

Nobody seems to expect you to keep your word (oath) anymore. (pity)

Sometimes the rewards aren't worth all the effort (level 12 lock).

Sometimes the solution is simple, we just want to make it complex (chain bridge puzzle).