Use both brakes each time you slow down or stop. If you use only the rear brake, you may never learn how to use the front brake properly when you need it.
Squeeze the front brake and press down the rear brake smoothly, gradually increasing pressure as needed. Jerking the front brake or hitting the rear brake hard can cause the brakes to lock up, resulting in skids and control problems.
Apply both brakes simultaneously. Many riders believe the rear brake should be applied first. On the contrary, the sooner you apply the front brake, the sooner you slow down.
Complete your braking before entering a turn, when possible. If you need to brake when turning, you can use the front, as well as the rear, brake, as long as the road isn't very slippery and you apply the brakes gently - you've less traction available for braking when you're leaning the bike.