Start your walk or run slowly, work up to a brisk pace, then cool down by slowing down for the last few minutes. Wear a helmet at all times. Obey traffic laws. You have all the same rules and responsibilities on a bike that you do in a car. Ride slowly on sidewalks and trails.
Pedestrians have the right of way on all walkways.
Never ride against traffic. It is against the law and motorists are not looking for cyclists riding on the wrong side of the road. Don't pass on the right. Motorists aren't expecting it and may not see you. Always use hand signals.