When you stop in traffic, put your left pedal down. As you slowly roll to a stop, put all your weight on that left pedal with your leg straight, then come forward off the saddle and put your right foot on the ground. It's OK if you are still rolling a bit, just dab with your right foot until you fully start. Stay astride the bike.

There are two ways to get going again. One is to push yourself forward with your right foot, dabbing, but not sitting on the saddle, until you get going fast enough to balance. Then sit down and start pedaling. Another way is to use your left toe to bring the pedal up to the 10 o'clock position. When you want to start, put your foot on that pedal and push down. At the same time as you push down, use the force of the push to lever yourself back onto the saddle. You can use a little push with your right foot at the same time as you push down with the left to get yourself upright and pointed in the right direction.

Practice in your driveway or in a parking lot. And of course you are wearing cycling gloves and a helmet.