You start by having your weapon holstered and concealed by the time the LEO gets to the scene (about 15 or 20 minutes after the shooting in my area. Much faster in some jurisdictions). You have your hands up and out when the LEO approaches. You tell him you are the one that called this in. (you did call this in, didn't you?) You do EXACTLY what he/she says to do, Including laying on your belly and your hands laced on your head and your ankles crossed if that is what they want.
You also need to gauge their level of excitement and don't do anything to increase that level. Answer all of their questions accurately in a calm voice. Stay as calm as possible. Remember he doesn't trust you and is looking for you to do something stupid. Don't do that.
If he asks if you are armed, tell him where it is (calmly) and make absolutely NO movement toward the firearm AT ALL for ANY REASON. If you are asked to crawl toward him/her, do it. IF your pants are coming off from crawling on the ground, let them fall off. DO NOT EVER NEVER EVER reach towards your belt to pull up your pants. LET THEM SUMBITCH"S fall around your ankles. If your Johnson is hanging out. LET IT HANG. Police officers male and female alike have seen plenty of naked people.
In other words do everything possible to defuse the situation. The main event has already happened. YOU are no longer in control when the police arrive THEY are. The sooner the police are calm and reassured, the better off all will be. You may be way smarter, and way more experienced than they are. So prove it, and defuse the situation.