It's not us you have to convince - it's the 12 little old ladies that will be hand picked by the prosecution.
But you asked for suggestions: Here are a few.
1. Get a bluetooth capable phone with voice command. Use electrical tape to cover up the flashing blue ring that all bluetooth devices seem to have. Then when you ARE on the phone, nobody will be able to tell. Just tap the call button on the earpiece, tell it do dial 911 and you're connected. It also helps you to have the second hand free for a problem while staying in communication.
2. Cover, cover and more cover. First and foremost in your mind should have been to seek cover - lacking that, seek concealment.
3. Make no eye contact with the bad guy, it's taken as a threat by most. I find it easy to assess someone's intent without looking directly at them, practice it.
4. Deal with the facts that you KNOW, not the things you THINK YOU KNOW. You only knew - from your account, that the guy was verbally agressive and threatening, you didn't know he was high or drunk or that he had beaten his girlfriend up. You do know that the person he has agression towards seems to be safely behind a door. He was a missile in search of a target - getting out of his range was/is important. You know very little about him or the situation at hand, aside from his aggressive demeanor. Drawing conclusions to justify your actions, when those conclusions are based on supposition is what can get you arrested.
5. Get a copy of the statutes dealing with the use of deadly force in your state. THINKING you know what the law allows and KNOWING are two different things. What you had in front of you was an apparently unarmed man who was angry. The idea that you might have to shoot someone is always going to be there, I am no advocate of retreat when there is a life to be saved, but the only life in jeopardy there was yours - taking a stand rather than seeking cover could have ended your life. There are a lot of shootings out there - and there exists a significant chance that you would have missed him, or whatever shots hit him would not have stopped him, you have to think at least two steps ahead of him/it. Could you have, perhaps, continued down the street and increased the distance between you without ricking exposure? Retreating towards the home is instinctual, but it also means you are putting yourself into a box. It was probably the best thing, but you must think about keeping your options open.
7. Get/keep/use a high powered flashlight. Surefire makes something called the G2, pretty inexpensive and polymer. It comes with the P60 bulb/reflector assembly. Buy a P61 bulb assembly - it makes the normally bright G2 EXTREMELY bright, blinding even - it also cuts down on battery life from about an hour to 20 minutes. People who can only see purple tend to hesitate and pause, it also helps you distract them while seeking cover, not to mention the advantage you have at night when you need to positively identify a person or object.
8. Pepper spray. not all encounters are deadly, it works against dogs and two legged dogs - if you manage to get upwind of a two legged dog, you have a LOT of distance you can spray, I recommend the fogger type. It also helps to show that you had a second form of force available to you in an encounter, lets say you DO shoot someone who desperately deserves it. Being able to show, in court, that you had a choice in the level of force is important - otherwise you can be painted as someone who literally had no choice but to shoot someone in ANY encounter.
9. Remember that in domestic violence situations, the next morning the odds are that the woman will be back in love with her husband/boyfriend - and YOU will be the bad guy that sent him/it to jail or hurt him/it - the victim in a DV is NOT someone you can count on to back up your story when the smoke is clear.