Personally, I never ride on the sidewalk. If there isn't a bike lane, you will obviously have to ride in the same lane as cars. Never split cars, ride to the front, etc., because it is so easy for somebody not to see you. Also, if people pass you safely once, you don't want to make them try to do it again. I ride about 1 1/2 to 2 feet to the left of the white line, mainly to force cars to get over as they pass, instead of making a bike and car fit side by side in the lane, and to be more visible. If there is a bike lane however, I ride to the front but I won't pass somebody after the light has turned for fear they will turn without a signal as they reach the intersection. If you can, wear something fairly bright if possible. The biggest tips I can give are to never assume you are seen and always assume the cars around you are going to do something stupid, so be prepared for it.