Participate in the Creation of a Walk Through Checklist
Sign and date it. Make a copy. If you can't find a copier take a photo with your phone.
If the place is in bad shape, don't move in
Unfortunately there are people who will try to rent a place that is a mess. If this happens to you, don't spend time doing the landlords work - e.g. cleaning the place up - just demand your money back and find another place.
Tell the landlord in writing if something breaks.
Go through the house or apartment carefully with your landlord. Don't be polite, be honest. Take pictures. If there is a disagreement you don't want this to be a credibility contest. Look under the sink and at the back of the refrigerator. Check the outlets, make sure they work. If there is a problem get the agreement to fix the place in writing and have your landlord sign it. Keep a copy for your records. Even if your landlord is standing next to you watching your water heater explode, write to him about it. If you broke something, fess up and fix it.
When you move out hire a cleaner
who will make you an invoice showing what you paid them to do. You can find a professional who will scrub out your place for a very reasonable price. When they are done take pictures. Keep a copy of their invoice so you can prove what you had done. You should tell them to clean the place, less normal wear and tear.You are not responsible for replacing light bulbs and re-painting. You are responsible to clean up your mess.
Your landlord's duty is to tell you his plans for your deposit within 14 days of when you leave.
You do not have to provide your landlord with a forwarding address. They have an address for you. Your duty is to tell the post office to forward your mail. You don't have to alert your landlord to his obligations regarding your deposit. That is the landlord's job.
If you don't get your money or a letter in 14 days, sue.
See this Legal Guide for instructions on how to sue to get your security deposit back in Washington State: http://www.avvo.com/legal-guides/ugc/how-to-get-your-deposit-back-in-small-claims