Finding an address in Portland can be easy. Almost all addresses in Portland, and even extending for miles beyond the city, include a map quadrant--NE (Northeast), SW (Southwest), and so forth. The dividing line between east and west is the Willamette River; between north and south it's Burnside Street. Any downtown address will be labeled either SW (Southwest) or NW (northwest). An exception to this rule is the area known as North Portland, which is the area across the Willamette River from downtown going toward Jantzen Beach. Streets here have a plain "North" designation. Also, Burnside Street is designated either "East" or "West."
Avenues run north-south and streets run east-west. Street names are the same on both sides of the Willamette River. Consequently, there is a Southwest Yamhill Street and a Southeast Yamhill Street. In northwest Portland, street names are alphabetical going north from Burnside to Wilson. Naito Parkway is the street nearest the Willamette River on the west side, and Water Avenue is the nearest on the east side. Beyond these are numbered avenues. On the west side you'll also find Broadway and Park Avenue between Sixth Avenue and Ninth Avenue. With each block, the addresses increase by 100, beginning at the Willamette River for avenues and at Burnside Street for streets. Odd numbers are generally on the west and north sides of the street, and even numbers on the east and south sides.
Here's an example: You want to go to 1327 SW Ninth Ave. Because it's in the 1300 block, you'll find it 13 blocks south of Burnside and, because it's an odd number, on the west side of the street.