Obey traffic lights (of which fewer stand in Lisbon than in Regina), and drive on the right. After that, pretty much anything goes. Park on sidewalks and in the middles of streets (in either direction or, in the case of the many smartcars, perpendicular), as long as room is left for at least a single line of pedestrians on the sidewalk and single lane of traffic on the street.
You'll thus encounter frequent multi-point backing up and turning, for which you wait patiently--having no doubt engaged in such maneuvers yourself today--unless the driver stalls or takes too long, whereupon you lean on the horn. As soon as you can, step on it. Expect tailgating and lane-hopping, even from buses and trucks.
Pedestrians on the often-narrow sidewalks run a system of their own--especially in times of umbrella (which everyone carries)--involving stepping down onto the street to let someone pass, or into a doorway.
All of this is highly unregulated, by North Am standards. Forget crosswalks, walk signals, or other rights of way. What matters, at least on streets and sidewalks laid down centuries ago, and on hills, is what and how you (as driver or pedestrian) communicate with the other. And quickly.
For highly regulated movement, check out the film called "Jewels", a three-part Balanchine choreography for the Bolshoi Ballet. Gorgeous.