When riding your bicycle on any road it's a very good idea to be predictable and let others, especially those in cars, know what your intentions are. You can let them know by using hand signals.
Put your left arm straight out and level with your shoulder. Once you are into the turn, you can let down your arm and return your hand to the handlebar.
Before turning right, put your arm straight out at shoulder height and bend your elbow 90 degrees with your hand pointing toward the sky.
Extending your left arm out and down indicates to those behind you that you are going to slow down.
Be sure to alway do a check over your left shoulder before getting ready to signal -- it's a good idea to know where the cars are around you.