Something you may not know, but when police are involved in a shooting, their union/guild almost always gets an attorney to the scene for the involved officers immediately. There is a reason for that. People (prosecutors and the victims families to name some) are often looking to blame someone for the shooting. This is even more true for the civilian in that you can add police to that list. And a shooting is a traumatic event and you are not going to be thinking clearly. Your attorney will. Your first words, no matter how much you feel they may make you seem guilty will be, "I'm sorry, I would love to talk to you officer, but I feel like I need my attorney now to help me because I am so distraught and upset." You can shorten this up to "I need an attorney" because its easy to remember, but I know that most of you will read this and think that it makes you look guilty. It might, but its a lot better than trying to deal with the police alone no matter how justified the shooting.
Don't brag about your gun, especially in a forum that's eternal
I read a lot of gun posts and am amazed about the number of people who post stupid things that could be used against them later in a self defense shooting. Facebook, blogs, things like that. They are around forever basically. If you post something stupid and then have a shooting later, those posts can come back and hurt you. So don't do it. There are prosecutors who would love to have that evidence in their case against you. Don't give them free evidence to make your justified shooting in jeopardy.
Don't name the gun you will use for self defense in a public way
There are a lot of people who get guns and name them. This is probably harking back to the days when swords and other melee weapons had names (or at least harking back to the books people read when they were younger that made people think that back in the day weapons had names). These aren't those days. This can come back to bite you big time. If you need to name your gun, do it in your head. And in such a way that you don't reveal that in your head you've named your gun. And if you have to name your gun AND let people know, buy another gun similar to it and DON'T name it and carry/use that gun for self defense.
Do get training as soon as practically possible when you buy a gun for self defense
There are millions of Americans who own guns for self defense who do not have a lick of professional training when it comes to that. This is flat out stupid. I'm going to leave out any reference to gun handling or stress training and just focus on the legal side. In Washington, and in most states, a description of the training that you go to for self defense and your instructor's opinion of how you did in that training would be admissible in court in your self defense case. In Washington, your state of mind is at issue and what training you received would help a jury know what you knew when you acted. For most shooting, this would be very valuable information for your case. Get trained!
Additional resources provided by the author
There are a lot of great schools in the area. The Firearms Academy of Seattle in Chehalis and Thunder Ranch in Oregon are just two of the biggest. Use them.