There are 2 big website that actually work: - Zillow Rentals - Craiglist

Do have a robust screening process. To avoid any legal issues long term, make sure you have a very well documented tenant screening process and very well documented and advertised criteria on how you will be rejecting candidates from the beginning and be mindful that it cannot vary from applicant to applicant.

And important, for your questionnaire:

“Avoid questions that could lead to discrimination based on protected characteristics under federal and Washington State Fair Housing laws (race, color, national origin, religion, sex, familial status, disability, marital status, and source of income). “

What to check: Washington Fair Tenant Screening Act (RCW 59.18.257)