If you are using an Asian squat toilet, make sure your pockets are emptied of items that you want to keep.
If you are running full speed through an English university residence hall, watch your head; the doorjambs are lower than you might think.
If the police officer who's just stopped you for DUI suggests it's a nice night for a walk home, agree with him; go for a walk.
If you purchase soup from a local supermarket deli, don't assume the cup they put it in is water-tight; do not rest the cup on expensive trousers.
Please add your own advice in the comments field.