I tend to stick to side streets, but occasionally the commute leaves me with no other options. We have a lot of one way streets through our downtown. In a way they are great for riding with all the available lane options for drivers to get around you.

As others said, take a lane and be assertive. I typically ride about where the right tire would be on a car. When I approach a red light or stop sign, I gear down and merge over to take the full lane and be visible at the intersection. Eye contact helps, I've found, as you approach intersections with stopped traffic and you have right of way. I stare the drivers down so they know I am there. Lights help with this as well.