Name the contents
Use plain labels that match the actual items. Do not rely only on colour if another person may use the box. Protect sharp components and keep a clear separation from personal supplies. The purpose is to reduce searching and prevent a casual reach into an unclear compartment.
Keep relevant information
Save specifications or instructions where they can be found again. A label does not decide what is legal at a waterbody. Check the current official source before selecting permitted equipment for the actual outing. Storage and permission are different questions.
Review the arrangement
Notice what was repeatedly moved or difficult to return. Change one label or division rather than replacing the whole system. A good arrangement should remain understandable after a month, when the memory of why you first organised it has faded.