If you are carrying packages, school books or anything else use a basket, or back-pack and keep both hands on the handlebars. You should know your limitations. Know what you can and cannot do. Do not take chances and watch what is going on around you. If you can, avoid riding after dark or if the weather is bad.
All cyclists are at a greater risk during the hours of darkness and in ba weather.
If you have to ride after dark your bicycle should be equipted with a headlight and also some kind of tail-light. Make sure that your bike is in good repair. Check and adjust loose parts and tire pressure weekly. Clean and lightly oil moving parts regularly. If possible always store your bicycle indoors, this will also keep your bicycle from being stolen.