Every time you set off, make sure you have a full first aid kit with you containing all the items you might need for your particular ride. Because let's face it, you won't need the same medical kit on a short ride close to home as you would on a world tour.
The point of the first aid kit is to be able to patch yourself up after a fall or help out another cyclist who's in difficulty.
Here are a few ideas to get you started. A good first-aid kit should be watertight and at the very least contain a pair of gloves, a pair of scissors, some disinfectant, several compresses and dressings, some plasters, a nylon bandage, a survival blanket, and a small bin bag or freezer bag. If you're travelling further afield, add to that some sanitiser gel, saline solution, tweezers, arnica, mosquito repellent and/or bite cream, sun cream to prevent sunburn, painkillers and anti-inflammatories, sickness and diarrhoea tablets, a tick hook, biafine cream, and a whistle to attract attention if you get lost. Finally, check your first-aid kit's contents regularly.