1. Loose with its two "o's" should remind you that there is too much space so something is "loose" as in a pair of loose (or roomy) pants. Loose also can refer to a handful of coins that are unrestrained as in "loose change." Similarly, a person may be described as "loose" if he or she functions with few rules or boundaries.
2. Lose with only one "o" should remind you that something is missing as when one loses or becomes unable to find or keep something or fails to achieve, as in "to lose" a game.