I've done many games by myself in the past. You need to be with the play as much as possible but also be aware of what might be happening behind the play. You have to be confident in your calls and also call it a little tight early. Leave no wiggle room for guys to start taking liberties. Any bullshit after the whistle puts someone in the box and never be afraid to tack an extra either on the guy who started it or the guy who decides he wants the last shot that keeps anything from cooling down. Be vocal when any kind of gathering happens around the net letting guys know that you've got X player for the original and telling them the next shot or whatever is also going. When I've spotted a delayed call for any physical penalty (rough, slash, etc.) I'll let out a "I've got him, skate away" or "Don't retaliate, I've got him."
One of my favorite memories was doing a midget select game (here that is 16-17 year olds) by myself. I was sweating more than any player at the end of that one. About a week after I saw the guy who put me on that game and he asked me, "what happened in that game?" I told him nothing special and asked why. He proceeded to tell me that he had heard from both teams that is was one of the best officiated games they had in quite a while.