Alright first off, I'm not an expert at throwing parties, this is just from personal experience. Getting straight to the point here is 3 things that you should do if you're having a party.
1. Dim your lights and tap them down, nothings worse then showing up to a party with the lights fully on, it ruins the vibe! Another thing that kills the vibe even more is having the lights off or dimmed and some drunk girl bumps the switch and it turns the lights fully on blinding every drunk person in the room (which should be everybody), so make sure you tape your light switches down.
2. Hide your valuables! I know this may seem obvious but damn, you really can't trust anyone. Anything that you don't want stolen put it in a different room and lock the door because people don't care they will take it.
3. Don't be a dick, like c'mon everybody's just trying to have fun, don't be that one person cock blocking or trying to start beef with everybody. If you see that person make sure you throw them out real fast.