word choice - How can I remember the difference between "loose" and "lose"?

Although both words can be found in dictionaries, I'm constantly forgetting which one is which.

Are there any mnemonic rules that would help me remembering them?

Answer

Lose has lost one of its o's.
Loose has an extra o, like an extra hole in a loose knot.

(Honestly, though, remembering just the first one should be enough to get you through everyday life).