The thing that i find useful is just to take screen shots and save them. I will always launch ASAP and take a screen shot of my squads. The best way is to take 2 screen shots. The first must include the loading screen, time and just a glimse of your squad attacking. The next screenshot must show after it refreshed and your squad is the only one attacking it. This way there is no way to doubt that you attacked first.
I know it may sound like a little bit of a pain, but with tools like LightShot it is actually ridiculously easy and painless to do it.
thats right good idea i get called sniper all the time