Seattle Landlord Associations and first rental agreement?

[Dan L.]

Hi, I recently got a place where I can rent out the other unit, and was looking for advice on getting a good lease agreement and getting started. 

Is there an agreement that someone could recommend?

Also, I came across 2 landlord associations: 

http://www.walandlord.com/

http://rhawa.org/

Are they worth joining and if so, which one should I join?

Thanks!