• Make sure your lights (both front and rear) are clean.
• When you have to carry anything on your cycle, use a bike bag or panniers.
• Make sure that your clothing or anything else doesn't get caught in the chain or wheels.
• Bicycles are an engineering work of art, the most efficient machines for
  directing human energy that we have invented. A proper operating bike is
  designed for silence, any noise communicates a problem.
  
• To get the best out of your bicycle you need to maintain it. A properly
  maintained bike makes riding more pleasant and safer.
• Have your bicycle serviced by a bicycle mechanic at least once a year and
  anytime a serious breakdown occurs. Young riders will need help in some aspects of maintenance.

When maintaining your bike, the first rule is do no harm:

• When cleaning your chain or lubricating any part of your bike ensure
  lubricant doesn't get on your rims -- it will prevent the brakes from
  working and can lead to crashes.
• Wse fixed size spanners rather than a shifter so you don't burr the edges of the nuts. If you are truing a wheel, use a spoke tool of the correct size
  for adjusting the spokes because the metal is soft and damages easily.
• Don't over-tighten -- most parts need to be tight but not over tight.
• On your chain use a specialised chain lubricant, not household or motor oils, which get sticky and attract sand that wears out the chain.
• Find out where each part lives and what it is called.