The first step, whether using fresh or canned, is to drain the tomatoes. (But don’t throw that liquid out!)
Fresh tomatoes contain an abundance of liquid, and a can of tomatoes contains more juice than solids; draining simply jump-starts the flavor concentration process since the tomatoes will break down and create a thickened sauce much faster when not swimming in liquid from the start. (If you like, you can further deepen the flavors by caramelizing some of the tomato solids in the pan before adding the other ingredients.)