first aid supplies on hand is to purchase a first aid kit, preferably from the American Red Cross. Don't think that you need to buy a first aid kit however, just to have one on hand. You can also build your first aid kit from scratch, adding in the necessary supplies to handle a number of minor injuries and emergencies.
You should have a first aid kit in your pets, having the right types and sizes of supplies. If you are a parent, opt to keep a basic first aid kit stored in your purse or diaper bag so that you have the right supplies to treat slips and falls when at the park or museum.