The laws vary from place to place. In my town and state, when I am on the road I have all the rights and responsibilities of a vehicle. When I ride on the sidewalk I have all the rights of a pedestrian and the additional responsibilities according to the law. For example. Use care overtaking pedestrians, pedestrians have the right of way on the sidewalk, sound out a warning when overtaking a pedestrian. Etc. The laws pretty well cover how to ride here. Some of the posts here said to go walking speed Exactly! If there are many pedestrians it's dangerous. If you go faster than the pedestrians it's dangerous. The law here also allows for it to be prohibited by posted signs.
In most places it's safer to ride on the road. There is a certain amount of judgment required, the law has many restrictions, read them. I rarely ride on the sidewalk.
Being visibly and easy for the car drivers to predict is a safe way to ride in the road. It actually makes the car drivers feel better about you being in the road. I suggest the brightest jacket or jersey possible and a daylight visible taillight and white front flashing marker light for traffic. Some cars and motorcycles have the lights on all the time this is because some research has convinced the manufacturers that having the lights on all the time increases your visibility.
Go on to your town and state web sight and read the bicycle laws. I live in Rhode Island I found mine. My state also has laws pertaining to a Segway type vehicle.